you explained it well enuff that I think you're being misled and that maybe you don't understand what they're offering - "epoxy powder coat thing" doesn't sound like something I'd find available anywhere
I'm familiar w/ the powder coat process [which is really paint minus the liquid] and their ovens [3-400 deg], and that they may use phosphate coatings between stripping and electrostaticly covering w/ powder, but there is no primer involved and epoxy primered materials cannot be powder coated, so they're offering something totally seperate from the powder coating process - like I said, you need to dicuss price w/ a couple body shops and see what the range is for paint and rust removal and true epoxy priming, and find out if any professional metal worker thinks an oven will remove much paint, or that any kind of coating done w/ the powder coat process could act like a primer and be painted over - powder coating can't be painted
Bill