AR build for a Vet

[XxWoodsHunterxX]

I'm putting together a build for my brother in law. I want to make it a memorial build for a buddy he lost while they were in Fallujah. He is trying to raise four kids and doesn't have the money to spare but always talks about buying a AR. I'm basically trying to find take offs people have they are willing to part with at a decent price. Any help will be greatly appreciated and will post pics during progress of the build.