Any gun with a .473 bolt face and long action will work. 30-06 etc....
$200 will NOT get it done.
Aftermarket barrel....$150-$400 Shaw, Hart, Shilen, Douglas, Lilja. Broughton....the list goes on
Chamber and fit $150-$350
Places like PacNor will do all the above for $500...I think.
For another $300 on top of gun purchase, you MIGHT be able to get it done......MIGHT!!!!
Kyle