I'm soon ready for high build as well and have been researching - may I ask what you're shooting?
Jon,
I'm using a combination of products on the interior and fiberglass of the airplane.
I'm using Southern Polyurethanes' Epoxy Primer over the SW wash primer, unprimed aluminum, and fiberglass. About $200/ two sprayable gallons. It gets good reviews and has performed well for me, both in being user friendly and appearing to bond well to the substrate and subsequent products. Here's a link (the product is at the bottom of this page):
http://www.southernpolyurethanes.com/products
I've used two different topcoats on the interior. One was Summitt Racing's Hot Rod Flat Desert Tan. I liked the way it sprayed and finished, but the color was a little too yellow for what I wanted. I'm probably going to use their hotrod grey on the inside of the cabin top and maybe the rest of the interior. Not sure yet. Here's the desert tan:
https://www.summitracing.com/parts/sum-up351/overview/
The other product I've tried on the interior is Kirker urethane in grey. It sprayed very well and I wouldn't hesitate to use it on the interior of the airplane. If I was on a really tight budget, I might use it or one of Summitt's gloss products on the exterior as well. The Kirker single stage urethanes (and color chart) are here:
http://www.autobodytoolmart.com/ultra-glo-acrylic-urethane-enamel-paints-c-1453.aspx
On fiberglass, I'm using this high build primer on top of the micro, epoxy wipe, and epoxy primer. Again, from Summitt Racing. When I can keep the gun from clogging, it goes on well too.
https://www.summitracing.com/parts/sum-up220/overview/
Depending on who you talk with, the paint and primer from Summitt *may* be re-labeled Kirker products. In any case, all of the Kirker and Summitt products seem to play well together, and I haven't had any problems other than spraying the really thick high-build primer.
BTW, the Kirker and Summit products are relatively inexpensive (vs the big brands), as are their reducers, activators, etc. Their story is their products are very comparable to the name brands from a performance standpoint, but the end user doesn't have to cover the expenses from advertising, broad distribution channels, or a wide network of brick and mortar paint jobbers.
For exterior paint, I have a deal worked out with a friend with an aircraft paint shop located at my home field. I'm supplying an airframe (in pieces) ready to paint with all of the sanding, filler, etc. complete. He's to take it from there.