How much do most tax preparers charge?

I'm curious to know, what's the average cost that individuals typically face when hiring a tax preparer to handle their cryptocurrency transactions? I've heard that the complexity and volatility of the market can drive up the fees, but I'm interested in getting a general sense of how much I should budget for this service. Do tax preparers typically charge a flat fee, a percentage of the transactions, or some other method for determining their compensation?