I agree with the advice AgentTikki and mjkeat gave. If you want less recoil than the AK/7.62x39 then I'd definitely go with 5.56 in some of the heavier loads and a 1/7 twist barrel. Glad to hear you've distanced yourself from the C15 and hopefully the shop that was trying to push it. $900 can get you a great AR and BCM comes to mind. PSA is a great choice and will get you down to the $700 range.
As far as the difference between the AK and AR I don't notice that much difference in recoil but I do feel like I'm in slow motion with the AK while the AR is much quicker with a followup shot. The AK action just seems slow and of course slightly more recoil.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek