I bought one from them with a 80% lower--$323 shipped to my mailbox'troglodyte wrote:Ceratac has a carbine kit (less lower) for $299 ($323 assembled) plus free shipping. Comes with a keymod handguard and collapsible stock.
Depending on what lower you can find and how much assembly you're comfortable with you could have a budget AR near your budget with a couple of little upgrades.
Pretty easy to mill the lower and have been happy with the gun so far, shoots and functions well.