Edited: I did not read the OP properly, misleading title. Shop price % changes would be dope and would mean that when there is inflation, that does happen during a playthrough, we can adjust without clicking a million times and doing a load of math.
Money is indeed problematic as it is, but I'll go with the other direction as Joe Glas below: There is no inflation in most situations given our 30-60 day cycles (that isn't a dead server), but rather in most cases we have cases of DEflation. Any new injected money as we have experienced so far has only resulted in increased societal propensity to produce and spend, thereby expanding the economy. The argument "We have statistics of trades and transactions" is also a bit of a misnomer. We have DATA RECORDS of trades and transactions, but they have not nor cannot at the moment be aggregated to become effective economic statistics reflection regional, national, or global markets. To make that happen, we need a way to record, gather, organize, and present shop transaction information sorted by jurisdictions and inter-jurisdictions that show the size and scope of currency as well as real material flow. It'd be great to know just how many of each foodstuff, what kind of wood or stone, or how many CALORIES of food have been transacted over time in a certain region, as well as your more classical signs of economic activity represented by currencies and taxes.
Why would you want to simulate inflation? You get inflation if the amount of circulating money is more than the value of transactions. Example: You get a special paycheck (for example for corona or higher energy costs). Now there is more money than a) you used to need and b) than usual for the same lot of goods => prices rise, inflation. Your delivery boy has to deliver more parcels and earns more due to working overtime. So he competes with you on the market => prices rise, inflation. The more steps we add to this chain, the longer we have to deal with inflation. So the best way to end that cycle of inflation is to bring that money on the shortest way to Jeff Bezoz and his friends. They put it on top of all that other cash they don't need, take it out of the cycle and worth of goods (inflation) is regulated by available amount of money and goods again. Money in eco is a bit problematic, because though we have statistics of trades and transactions, the cycle of a server is a bit short for adjustments. Most currencies are backed with stupid stuff, because it actually works better than something rare. Remember: If productivity reaches a new lvl (plow, tractor, ...) we have to adjust the amount of money to keep prices stable. This can easily be done if the bank buys 100 rice and emits the needed amount of money, but it can't be done if you need to buy for example 100 super special lasers to raise amount of money by 1 %. Side note: That's one of the reasons why Bitcoin can never be a currency. On the other hand the whole money system is in the hand of the person who can mint trash into currency. That's the really extreme version of MMT (Modern Money Theory), where we trust in a whole system and not just one person. But in the end: Why do you need a currency in eco at all? All we want is to save the planet. There is no benefit in hoarding a currency. I like the early game credit system. And if I see that someone works hard to save the planet, he can have my stuff for free.
Very good suggestion. Would love to see this.