Don't wait. Go now.
“Get your butt down to your local shop and buy an AR-15 lower receiver. ATF considers this the gun and everythign else is unregulated parts. They build easy with no special tools, anyone can do it. Cost should be less than $150”
Well, no. The lower receiver, cause it has the serial number, is considered the firearm and all paper work to buy the receiver is the same as buying the whole weapon. The time you buy the parts needed to finish the ar, you can pretty much purchase a less expensive weapon like the S&W, which is a fine weapon regardless of price.
But, if you choose to build, it is a great way to get to know your rifle.
That was my thought as well, but after a quick glance at my favorite resource, it might be harder than you think.
http://www.riflegear.com/c-94-stripped-lower-receivers.aspx?pagenum=1