One of the things that was pointed out last time was that the by-the-book OD&D money structure of 1:10:50 (gold:silver:copper) was passingly similar to the real-world coin values in medieval England of about 1:20:80. Note again that this is separate from the often-confused issue of "moneys of account", i.e., pounds/shillings/pence at 1:20:240, which were used for bookkeeping purposes only, and not actually coins. We consider it a mistake to use those ratios in AD&D for several reasons. (And thanks to commenter Tsojcanth for pointing out that GURPS also uses the historical 1:20:80 coin conversion rate.) Our OD&D coins more-or-less match the English silver "Groat" (4 pence, 1/3 of a shilling) and gold "Half Noble" (40 pence, 1/6 of a pound value).
So here's what I'll be doing from now on:
- Convert the economy to a "silver standard". Read the OD&D Basic Equipment list as being priced in silver pieces, not gold (and start PCs with the same). Likewise, read the values for gems, jewelry, hiring henchmen, paying specialists, tolls and tithes, crafting magic items, etc., as being in silver pieces. Award experience at the rate of 1 XP = 1 sp.
- Reduce coin treasures appropriately. Fortunately, by choosing the OD&D conversion rate of 1 gp = 10 sp, it's simple to convert monetary treasures to an equivalent purchasing amount; just divide by 10. For example, monster treasure-types (Vol-2, p. 22) are now generated in 100's of coins, not 1000's. Do the same thing for other coin-specific tables, treasure troves in pre-published adventures, etc.
- Change the encumbrance rate of coins. Let's assume that our money weighs an average of 100 grains per coin. This is realistically large: 6.48 grams per coin, 70 coins per pound, and 980 coins per stone weight. For simplicity, we'll say: 1,000 coins per stone in our streamlined encumbrance system. That makes it exceedingly easy to adjudicate. (Another benefit to the 1:10 gp:sp choice is that it accurately reflects the medieval value of gold & silver by weight, i.e., it's correct to think that our coins do in fact weigh the same amount.)
- Use historical pricing data to fill in gaps. Now that we have a more real-world based economy structure, it's reasonable to use historical resources like the Medieval Sourcebook to answer more esoteric questions when they come up in play. You'll just have to convert moneys-of-account to coinage: Where it says pence (d) use the same number of copper coins; where it says shillings (s), multiply by 3 for our silver coins; and where it says pounds (L), multiply by 6 for our gold coins.
Some of the lessons here, I think, are these: You don't want to "blow your wad" with enormous summer-action-movie-size treasures right at 1st level. A fat purse with a few dozen coins should be worth a thief's time to knife someone over. A wizard should be able to carry enough money in the folds of his robe to buy a night's stay at an inn, hire a lantern-bearer, or procure some interesting ephemera. If you want to jump into "heroic" adventure from the get-go, then it should match the rest of the D&D mechanics in that 3rd or 4th level is where you would start.
Pricing power, and therefore game-balance, is always exactly the same as in the regular game; a roll of N on whatever treasure table allows you to buy exactly the same number of helmets or horses (or whatever), and awards exactly the same XP, as in the base game. The one thing that's changed is carrying capacity -- characters can pack out almost ×100 greater value in treasure (×10 for the silver-standard switch, and ×7 for the weight-of-coins change). No longer do you have characters leaving the majority of a treasure in the dungeon at 1st level, and worsening geometrically from there.
Examples of historical conversions: Look to the Medieval Sourcebook. Leather armor in 1285 is listed as 5s (shillings): convert to coins by 5×3 = 15 silver pieces (historical groats), and notice that's identical to the OD&D equipment list. Helmets (Burgonet, 1590) were 4s: convert 4×3 = 12 silver pieces; compare to OD&D listing of 10. Draft horses (13th cen) are documented at 10s-20s: convert starting price 10×3 = 30 silver pieces; again, identical to the OD&D listing.
Lessons from this exercise: The OD&D price listings are actually somewhat realistic (at least on the right order-of-magnitude; usually within a factor of ×2 or ×3 or so) if you read them in units of silver pieces, like the historical "groat" coins. (But not gold pieces; nor shillings or any other non-coin money-of-account.) I think that's good news, because it allows us to leverage our wealth of resources from history to support and enrich our game in this particular context.
Now I'll point out a pair of outliers. One exception to realistic OD&D pricing in silver coins is the heavy armor types, chain and plate mail. While Vol-1 lists these at prices of 30 and 50 respectively, looking at the Medieval Sourcebook shows that they could realistically be valued at 10 times those figures in silver pieces. You could change them, but I'm conservative enough that I don't want to re-do the pricing list just for this. I'll be giving my players the price list unchanged from the OD&D books, merely referencing them in terms of silver instead of gold pieces, and running the game unchanged in that regard.
The other exception is the cost of men-at-arms. One thing that's apparent in OD&D as you look on facing pages in the DM's book (Vol-3, p. 22-23) is that the prices for Specialists & Men-at-Arms are in totally different magnitudes (the former in hundreds or thousands per month; the latter in ones or maybe tens per month). The costs for Specialists can be interpreted as silver/month and be compatible with the rest of our system, as usual (compare to Sourcebook: "armorers"). However, if we take the Sourcebook mercenary/army wages (usually in a few pence or shillings per day), add in a like factor for upkeep/support, multiply out to monthly payments, and then convert to our half-noble gold coins, then we get numbers very similar to the OD&D table. So this is the one case in our entire system where we should do the following for realism's sake: Read the OD&D Men-at-Arms monthly costs in actual gold pieces, not silver pieces (i.e., multiply by 10 for silver pieces).
One other note: If you'd prefer to use the 1:20:80 ratio in your own game, almost all of the foregoing would still apply, although you'd have to divide coin treasures by 20 (instead of 10). When converting historical prices you'd multiply both shillings & pounds by 3 to get your silver and gold coinage. And OD&D men-at-arms prices could possibly be cut in half (reading in gold pieces).
In summary, this fairly lightweight revision provides a lot of advantages: (1) We maintain by-the-book coin conversions for OD&D. (2) We can still use almost all of the OD&D tables and figures as written, simply dividing coin treasure amounts by 10 on the fly. (3) Game balance is maintained with identical overall purchasing power and XP awards. (4) We create a campaign where PCs can carry appreciably large amounts of value with them, whether in the dungeon, wilderness, or city (even when treasures are increasing hugely at the upper levels). And (5) We develop an economy and coinage reasonably in tune with medieval Europe, such that we can use historical sources to enrich and reinforce our game when desired.