Not to be too cynical about it (though it's hard not to be these days), but your current quotes sound pretty darn good to me compared to what I've been hearing lately.
Haven't seen any professional painters quote $5,000 to just put it in primer lately!
Not saying it can't be done, and it's the local guy that does it on the side you're probably looking for, but paint has been expensive for awhile. Even more than traditionally!
Just too much labor involved probably.
If you just want someone to shoot it and give it a twenty-footer paint job, do any of those discount shops still exist? Earl Scheib, Miracle, etc still around?
Paul