OK someone paid me to build one for them before and they wanted me to make it as cheap as possible. We can talk here in a bit and I can see what I can come up with. Truthfully if you could come up with a bolt carrier and handle I could probably pull this off. I am not counting shipping Spikes lower - 99 DSA M4 style upper - 275 parts LPK - 59 Stock and buffer - 39 (standard A2) Collapsible - 59-79 All and all you would be close. Will it end up being a 1000 rifle? No. Will it be a safe functional AR, Yes. Will it cause you any issues, no. Not in the grand scheme of things. God I hate to say this. You can order a Varient of a M4 from Delton in a complete kit for 465-485, add a lower and you are Golden. you can find cheaper lowers on the market but personally I would go with the Spikes. Ultimately you would be more toward the 650 mark with shipping and everything else. A lot of shops will charge you to do your transfer for the lower, Let me know if you decide to get one and I can direct you to my shop to get one, where they do no such thing. save you at least 20.00