I found building the -4 to be a great father-son experience, and since I am a certificated AP/IA, the repairmans cert. wasn't on my radar at all. My son now works for a local FBO at our home airport, and is preparing to get his A&P. He enjoys an occasional flight with me, but has not pursued getting his PPL at this time. I'm not sure how far along you are with your -4, but it isn't going to get cheaper to build one for sure...I would buy all the parts you can to get finished so you don't have as many stop-wait-buy-build on delays. The -4 still requires alot of forward thinking for systems, ect. that are more plug and play on other series of RV's.
8A7 / Advance NC