I'd just like to add that I would recommend Gaitorbait and the ones I've gotten from him are great quality and really add to a display. That and hes very easy to deal with in regards to what you want on them.
I've not dealt with any of the RPF members here (yet) but I've ordered no less than 50 plates from plaquemaker.com. Nothing fancy - typically just a black logo and text on a 1.5" x 3" metal plate with adhesive backing. I paid about $5 per plate.
If RPF members are even close in price, I'm due to order another batch for all the crap I keep finding in the junkyard!