It's not easy to do. I can tell you some of the hurdles you'll have to overcome.
First, most price lists are just random numbers pulled out of the air. This creates problems if the PC's get into manufacturing those items and can do so with a cost of production significantly below that of the published price. Realistic prices are a function of the living wage and the time and skill to produce and distribute the goods. Prices are essentially days of labor when you get down to it.
Second, the impact of spells on economies generally has not been considered, and so the rules for any spell with potential economic impact may need to be revisited.
Thirdly, the daily living wage is generally not set realistically in a typical campaign setting. After expenses, PC's are going to want to be earning a couple times more than the base line living wage.
Fourthly, while you can abstract out the daily cost of living to be a function of level based on the assumption that higher level characters have more expensive things they have to maintain, you'll probably want to have modifiers for that depending on what the PC's are supporting - steeds, retainers, excess property etc. Property at 1% of value annually or monthly isn't a bad rule of thumb. Steeds and pets should work out to X times the cost of basic support for a level character depending on the size and type of steed and retainers usually cost more to retain than the standard of living of an equivalent level PC (because the NPCs want to turn a profit).
Fifthly, you'll want to give some thought to taxes. Roughly 30% of income should be going to taxes and fees of various sorts.
From all that you can then work out what sort of wage that the PCs have to pull to cover basic expenses. So as some starting points, the daily living wage in my D&D campaign is 1 s.p. and a 1st level PC has 1 s.p. worth of maintenance costs to cover per day to keep clothes on their back and fed, etc. For the purposes of prices, 1 s.p. buys roughly the equivalent of $50 worth of handmade non-industrial goods such as produce, prepared foods, livestock, hand-made furniture, hand tailored clothing, hand tooled leather ect. Quite a bit of things translates, for example fight quality weapons and armor are generally hand made these days because of low demand, so many times you can work out realistic prices pretty well. Prepare for the PC's to be shocked at how valuable things like clothing are.
If the PC's buy anything that exceeds minimum expenses for their level, that has to be paid for in addition. Typically, what you find is that PC's have to make 3-5 minimum daily wages per day per PC to break even at low level. I typically use a 1 s.p./level rule but allow base expenses to include better quality accommodations as the PC's go up in level.
One thing that happens in this system is that PC's can earn effectively credit whenever an NPC is hospitable. So when an NPC buys dinner or offers to let the PC's spend the night, the PCs are effectively getting paid a portion of what they'd normally have to pay in upkeep.
One other thing you'll notice is that most adventures typically assume the PC's become extremely wealthy very quickly. Under the outline I just gave, a single gold piece in my game is $1000 (20 daily wages) and is treated like it is real money.
But in terms of the balancing act you'll have to do, you'll probably need to eyeball and come up with expenses or windfalls as needed to keep things more or less where you want them to be.
