On Support and Upkeep

Let's look at some old-school rules regarding PC support and upkeep expenses.

Original D&D

Gygax in Vol-3 says this (p. 24):

Player/Characters must pay Gold Pieces equal to 1% of their experience points for support and upkeep, until such time as they build a stronghold. If the stronghold is in a wilderness area all support and upkeep costs then cease, but if it is in a village or town not controlled by the player/character then support and upkeep payments must continue.

Here we have a fairly simple rule to simulate cost-of-living expenses for the presumably high-living adventurer; including a built-in incentive for one to build a stronghold at the topmost levels. The rate of the expense is not explicated, but we can assume it to be monthly, as it is in both the AD&D DMG and the Dalluhn manuscript (a version of a pre-publication for OD&D). One obvious, small gap with this rule: a 1st-level adventurer starts with 0 XP and therefore pays zero upkeep so long as they stay that way.

AD&D 1st Edition

Gygax in the 1E AD&D DMG changes the rule to this instead:

Each player character will automatically expend not less than 100 gold pieces per level of experience per month. This is simply support, upkeep, equipment, and entertainment expense. These costs are to be deducted by the Dungeon Master automatically, and any further spending by the PC is to be added to these costs. Such expense is justified by the "fact" that adventurers are a  free-wheeling and high-living lot...

The expense calculation is greatly simplified (a linear multiplier by level), and in so doing, enormously reduced in the long run (i.e., after 8th level). The other detail is that the savings from having a stronghold seems to be removed; the passage goes on to establish a 1% stronghold value cost per month, in addition to the preceding cost.

AD&D 2nd Edition

Dave Cook in the 2E AD&D DMG adjusted the rule to give players a choice of living conditions:

Even though this choice is given, as is the idiom for 2E, there are no specific in-game results of this decision; only some vague role-playing suggestions:

"The only direct game effect of living conditions is the expense involved, but living conditions can also determine some role-playing events and conditions in your game. Your player characters' lifestyles even can be used as a starting point for many different types of adventures."

D&D 3rd Edition

The 3E D&D DMG has a "Variant: Upkeep" in a sidebar (p. 142 of my copy), much in the spirit of the 2E rule. Here the options expand to 6 categories, and again, some soft role-playing suggestions attached to each are given, but no hard-and-fast rules. One change is that all of the category expenses are fixed values, including the topmost ones, such that none of them scale by level. The categories in question are: Self-Sufficient (2 gp/month), Meager (5 gp), Poor (12 gp), Common (45 gp), Good (100 gp), Extravagant (200 gp).

Basic D&D

To my knowledge, no version of Basic D&D ever included a rule of this sort. Searching Holmes Basic, Moldvay B/X, Mentzer BECMI, and the Allston Cyclopedia, I was unable to find any reference to "expense", "upkeep", or "support" in this context.

Conclusions

I think it's reasonable to have some (simple) rule for simulating mundane cost-of-living expenses to the resting adventurer. I am really not fond of the 2E/3E expression of a choice with no real in-game ramifications. One way of resolving this would be to draft a more full-fledged set of rules with some kind of concrete results from that choice -- like modifiers to abilities, checks, hit points, reaction rolls, different encounter tables, etc. (Somewhat in the vein of the infamous "carousing" rules.) Another path would be to say we're not really that interested in mundane details, and just strike out the whole system in favor of an earlier, simpler, choice-less accounting.

One thing that's interesting to note is that -- once again -- if we convert the OD&D rule to a silver standard, and assume 1 sp = 1 groat (i.e., 1/3 of a shilling), then the results are somewhat surprisingly more in line with reality than we first might guess. Check the following table:

Example expenses are taken by looking at the Medieval Sourcebook: Medieval Prices (currently here). They actually track quite well, as around Name level the expense resembles that of a Baron's estate, etc. The 1E DMG rule would not work this well, as its linearity does not reflect the exponential curve seen in a real economy, such as in the Sourcebook above (but nicely modeled by the OD&D XP charts, serendipitously).

So for my OED campaign I expect to use exactly the OD&D rule, as shown here. This removes any choice from the player and abstracts out the expenses to something we don't have to role-play around every month (indeed, it presumes our adventurers are a hard-drinking, hard-researching, and/or hard-tithing lot, with more rooms and servants as time goes by). It's reasonable to set a minimum 10 silver/month expense to fill in the gap for low-XP PCs (economically we could defensibly set this at 20 sp/month, but I think the round number is easier to remember and distinguishes from the 2nd level tier). I've also got a rough rule that if the PCs refuse or cannot pay this cost, then a −1 modifier to all ability scores is taken (but I'm open to some more refined, if equivalently simple rule on this score).