Greetings!
Well, I suppose it all depends on how *technical* and immersive you want to be in your camaign. Some questions for you, thus:
(1) Do you want something that is quick, easy, and useful?
Answer: If yes, then simply assign a weekly stipend of gold. Say, 5 GP/Character Level, per week. Obviously, depending on how developed your economy is, this figure can and should be tinkered with and adjusted, from say, 5GP/Level, 10GP/Level, 15GP/Level, 20GP/Level, and so on. For somewhat more powerful and exotic lifestyles, providing lots of opportunities, I would suggest somewhere in the 500-800 GP/week range. This provides the character with plenty of gold for traveling, bribes, occasional gambling, hosting feasts, banquets and parties, as well as ransoms, investments, buying a hot new warhorse for 2500 gold, impressing newly hired troops or hirelings, special commissions, and so on. It provides for all the basics, so the character must still go on adventures if they really want the *BIG* money!
(2) Do you want closer immersion and realism reflecting a more medieval, *rural* nobility?
Answer: Such *Rural* nobles tended to highly value gold and silver, of course, because while they could get it, and had some--it took a while for them to actually be able to get their hands on it. Why? Because their peasants supplied them with their taxes in the form of copper pennies, rabbits, lumber, bales of wool, eggs, chicken, elks, wolf furs, wagons of fish, cattle, lambs, pigs, raw ore, tools, crafted weapons, and clothing.
All of that had to be processed, and used, and what wasn't needed by the noble lord and his retainers with his own castle or estate, took time to package up, and take to larger markets in cities where through the process of trade and dealing, such goods could be turned into actual silver and gold coins, which would then be taken by caravan or other travel back to the noble lord, typically weeks or months later.
Thus, it can be relatively imagined that a rural noble would get *shipments* of silver and gold perhaps three or four times a year. Aside from these alotments of such coins, most of the time, most of his wealth was in the form of raw goods, animals, or services owed to him.
So, it depends on how you want to do it in the campaign.
Semper Fidelis,
SHARK