Remove trim as best you can, do as much prep work as you can, and offer to mask it.
Have them use epoxy primer by all means, as it provides the best base and is thick enough to even out the finish. Adds a small amount to the cost, but the paint's foundation should be strong.
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The best paint is Imron, no doubt, but there are other good paints. Get a two part paint as they cover better, resist runs, go on smoother, are more resistant to fading and chemicals, don't orange peel, and are worth the extra cost. Labor is what kills you and that is why you will save oodles of dough by doing that yourself if you can.
If you do, you should get a very good paint job with good paint for around $1,500.00 max. I paid $1,800.00 for Imron and 3 coats of Imron clear, after I did almost all the prepping. The shop did a once-over with sandpaper and cleaned it well.
Imron is such great paint that it resists car wash swirls, sun damage, and has a great shine. Looks better than new. Great metallic colors!