My problem has always been with the percentages used on certain things; like commissions. Just make it a flat fee. Things that require agent's time like open houses; bill for that. It's the essentially the same effort on a $100K house and a $500K house and a $1M house. Maybe once you get to $5M+ houses the fees need to increase since this is a different class of RE with much smaller pool of buyers. But still should be fixed amount and not percentages.

In my area, since I bought my first house 10 years ago house prices have 4X'd. I don't think the wages of most professions have, the demand for housing makes it easier to sell, so why should agents be making 4X more?