Early game you can't buy everything you want. The primary reason for this is you'll be investing in your keep and magic items are typically very expensive, with the less expensive stuff still being around 3k to 4k pands and the more desirable stuff like extra spell rings and weapons like Borresaine being around 10k+.
I typically only buy the less expensive upgrades in the keep in the early game and only buy key pieces of equipment. I then have all the money I need for things like rest bonuses, consumables, crafting materials, etc.
As time goes on money will stop being a problem. If you clear Readric's keep with a "kill 'em all" mentality then you'll clear tens of thousands of pands. Not all characters will want to complete that quest that way though.
Basically the economy was pretty well balanced in this game, you can't just buy whatever willy nilly and not expect to run out of money, at least if you are upgrading your keep. Even late game when you're rolling in money if you try and buy every single magic item you can go broke.