It would all depend on what you are trading, the average value of a Century L1A1 with the butthole stock is around $400, if even that. Also, you might want to check to see if it's built on an Imbel or Hesse reciever, all Century FALs are hit or miss with functionality, but the Imbel based versions seem to have had less problems than the Hesse. I have one of the later Imbel based rifles, cheap Century stock, not the Bell and Carlson butthole series, and it has worked from day one without a hitch. There are a few good options for the stock replacement, you can get the Century cheapo stuff, or, change a few other parts, such as the gas piston, mag floor plates, cocking handle, and add some original British or Aussie stock parts. A good place to find such parts would be Gunthings.com, they have everything you would need to do a swap out, and keep the rifle legal.