NewJeffCT said:
The players just saved a town and rescued the duke. As a reward, the duke awarded the players the ownership of a home that used to belong to a knight, but who had died in combat and left no family.
It's a decent-sized home, but not a mansion/villa/manor or anything like that - probably a very nice home for the medieval era in that it is about 1,200 square feet.
Square footage doesn't tell you much. That could be a wattle and dung single room thatched house with a bare dirt floor covered with straw. It might be little better than a barn for people. In fact, sometimes the animals might share the house.
Construction materials are the big difference between the houses of the wealthy and the poor. The king might live in chambers little larger than a peasant, with scarsely more comforts than warm clothes, but he has a tile floor and stone walls, plenty of firewood, and the space to himself rather than 12 people crammed into a room.
Grand House: 3,000-6,000 gp (4-10 rooms, thatched or wooden roof)
Grand Inn: 10,000-25,000 gp (9-32 rooms; wooden roof)
Mansion: 75,000-125,000 (no fewer than 10 rooms; slate roof)
Under the gold peice standard, you can imagine 1gp ~ $50.
So...
'Grand House: $150,000-$300,000'
'Grand Inn: $500,000-$1,250,000'
'Mansion: $3,750,000-$7,250,000'
Are those realistic totals at all?
No. Are they reasonable given the described economy of D&D? Yeah, probably so.
The gift of 'a house' is kinda wierd. It's the kind of thing you might give a widow or a mistress who either didn't need money or whom you didn't want to have an independent source of revenue. To a vassel, or potential vassel, you'd give a manor - a house plus attached lands and the serfs or tenants that go with it. The lands would pay for the upkeep of the house (so that giving the subject the property didn't amount to a 'white elephant'), plus you'd get a portion of the revenue back in the taxes owed on the property. The fact that your vassel, or potential vassel, had revenue producing lands on your land was presumed to be incentive for the vassel to protect your property as well.
If you haven't already specified that no lands go with the house, I'd reconsider not just because its more 'realistic' (and calculated on the part of the Duke), but because it is a very good hook for getting your players involved in politics, the doings of the peasants that look up to them (or not!) and so forth.
If you have specified that no lands go with the house, have it ultimately turn out that the reason the Duke is so glad to rid himself of the property is that some subtle curse is associated with the house. You can do subtle curses in a variaty of ways.
a) A curse that manifests itself only after lengthy inhabitation - say every six weeks save or be cursed.
b) A curse that is subtle, and unlikely to be noticed by a PC (or linked to the house) initially like sterility, all diseases gain +4 DC, greater chance of catching mundane diseases each month, healing magic targetting the cursed person is at -2 caster level, penalties on travel time, or all investments return 30% fewer funds. Naturally, removing the curse from the property requires doing some small quest.
c) A ghost or other dangerous being that manifests to haunt the house only infrequently, such as only on nights of the new moon, only during thunderstorms, only on the anniversay of the person's murder, etc.
Personally, I'd go with 'all of the above'.