So what you're after is a modded price setter with for example a single button that enters 20p in 1 press?
Mother's Pricing should provide what you're after without conflicts.
Extract his zip directly to your FetishNightfall directory. The posts to his download thread provide instructions on how to tweak the presets to your liking.
If enough people chime in that they want this feature, I'll see about including it standard. Maybe tweaked to be a bit more user friendly to edit the presets.