SwampyMO -- In order to LEGALLY build an AR in pre-ban configuration, you MUST have a preban receiver. Herein lies the rub... locating a preban receiver that is not already in full preban rifle form is akin to locating a genuine set of George Washington's wooden teeth. It is nigh on to impossible to do.
This, my friend, is INCORRECT! You can find a pre-ban lower quite often and easily. Go to the boards at http//subguns.bighammer.net . There are always pre-ban lowers for sale there as well as
www.ar15.com at the equiptment exchange.
The legal way to do it is to find a lower that was
ONCE assembled into a complete rifle before '94. This is not hard to do. A lot of the sellers have a letter from the manufacturer that states this. Or, you can find a lower that you want to purchase, ask the seller the serial number, then call the company. They can quickly and easily tell you the info you need to know.
Then, I am going to say this. Take it for what it is worth. If you find a pre-ban lower and you find out it was never assembled, then, I, personally, would not worry about it. But that is just me. You would have to practically murder someone for them to look that deeply into your rifle. I mean, if you are at a traffic stop and you have your rifle in the trunk, the most they will do is call in a SN check to make sure it is not stolen. They are not going to see if it were assembeled before '94! See what I am saying. But, if you wanna be totaly correct/safe, then keep it legal.
Good luck. I have built two myself and it is a lot of fun. I am going to be starting a 3rd soon. For your money, the best thing you can do is find a lower and then buy all the rest piece by piece off of Ebay! You will get it done the cheapest that way. I would not be surprised if you get everything you need, minus the lower, for around $400. But, be prepared to shell out the clams for that beloved lower. It will probably run you $600 stripped and upwards of $900 complete.
Enjoy!