Agreed, that's something that tickles me as well.
But I want something else besides gold. Something that shops can compete for. Maybe just very special and rare items? But they should be good for something.
How about trophies? From the endboss, parties can sometimes bring a trophy. You can buy these trophies (auction-style) and it will add to your shop rating, but not cost maintenance (like shop sections do).
Gold should be secondary, reputation should be everything. Then again reputation should be able to be converted to gold and vice versa.
