Joe,
I'm not body-shop expert.  I don't even pretend to play one on TV.  But good Lord, man, if you're going to sink as much time and effort into prepping your Westy for Maaco or Earl, why not go the extra few feet and complete the job yourself?  You're going to need about three-quarters of the tools anyway...

In order to give your repaint the best chance for reasonably long-term survival, you're going to have to do a lot more prep than just washing the bus.  Attaching the rust means grinding the area down to bare metal, treating it with some kind of rust inhibitor, priming, and sanding it.  If your bus has more than just a spot or two of seam rust, this whole process can become a major undertaking.

Never having had any dealing with either of these two businesses, I really can't comment on what they do and how they do it.  There are, however, reputations and second hand information floating about the list that leads one to fairly scream, 'don't whatever you do, go to these places!'  To get a decent paint job, the your bus is going to have to stripped of all attachments - mirrors, molding, bumpers, windows - prepped - meaning taken down to bare metal - primed, sanded, base coated, and finally top coated with a quality paint.  And this quality job is not available from a franchise without paying a hefty price for it.  The paint job you're looking for is not available at the price you're paying.  You're going to get a van that's been shot with a top-coat and that's about it.  You'll be lucky if they mask everything properly.

As an alternate, consider doing the job yourself by enrolling in a BOCES- or continuing education-type course at the local VoTech school.  Or perhaps contact the local VoTech to see if they would like to have a class project - painting your bus.

Sorry this is a little long winded.  I've gone thru this before.  Lowest price I received for a quality paint job was $4200.  Macco, on the other hand, quoted $700.  Haven't gone either way, but I am saving some $$$ for another vehicle (hopefully a MB 240D or 300D) so I can take my bus off the road and finally get the rust under control.  And it looks like I'm going the VoTech route...

Alan Bosch
& Phred ('88 Wolfsburg)