It'd be useful to be able to set this on a per shop basis. For example, if a user has wallet funds with a particular shop, normally they can transact without paying additional fees. It'd be useful if this site could show that without-fee price in its main display price (rather than the hover-over display).
I looked in the 'special discount' menu for this, thinking it might be available there. It seems like a similar kind of feature to that.