I've got lots, including a 16" bushmaster that I'd consider selling.
Some of the biggest questions are what you're planning to shoot, whether you'd rather use iron sights or if you plan to buy a scope, what barrel length you want (probably either 16 or 20 depending on its use), what's your budget. You can then move into what, if any attachments and extras you're looking for.
Don't limit yourself to wal-mart, just order it online and have it sent to american cash exchange on fort riley blvd. The fee will be about $20. If you have questions just ask, I've used most of what's out there for AR's. Once I know your budget and what you're wanting to use it for I could try to point you to a good deal.