I have a Russian and a Yugo SKS, both are great. I think you'll find the Yugo the most affordable SKS on the market right now and they shoot great, plus include the grenade launcher.
For an affordable ar, check out
www.del-ton.com I don't know much about them but most of what I have read has been decent. If anyone knows anything about these guns fill me in, I am thinking about ordering one of their 20" uppers.