This thread looks pretty old, but I would like to put my vote in for having a field in each product for a wholesale price. Then based on the group the user logs in as, show the regular or wholesale price. In my case each product can have a different amount off the retail price. There isn't a formula where you can say the wholesale person gets 10% of everything. It would be too individualized to make that many coupons.
Support did give me a workaround for now using one of the custom fields and if that field is filled in, show that price, else show the normal price.