You are gonna have to go through an FFL unless you do a private sale. You can check on AR15.COM Equipment Exchange section. You probably won't find one in the price range you named right now.
Just be aware the lower recommended to you is a Polymer Lower. Don't want to start a debate but most people prefer aluminum lowers. You can read the Polymer Lower Thread for more info.
"I disapprove of what you say, but I will defend to the death your right to say it." - Evelyn Beatrice Hall
Last edited by Bowfisher247; 02-23-2013 at 08:04 AM.