I'd rather start buying parts to what would eventually be something awesome like I've done with all my rifles the last several years. I wish I would have learned that lesson a long long time ago. That $300 would be a good start on a badass 5.56 AR. A high end barrel or high end upper or lower, down payment on a good scope, trigger... If you just want a small framed AR to shoot a lot and not be fancy then that $300 has you almost halfway to a beater AR. If you ask me, which I guess you didn't... They did you a favor not having it in stock. Put money into being able to shoot 5.56 in a heavy 308 platform? Don't do it.