Adam, do you know if you can just swap the bolt and barrel out to get a .243? I wonder if you bought it in the 22-250, you could buy a .243 bolt and barrel from someone (overseas most likely) and swap it in the same chassis/receiver.
My Blaser could easily interchange between the calibers it was offered in w/ simple bolt/barrel swaps, but they also offered all calibers for sale in the US.