Hello Clayton,
Turk Bros pn 555129 $71.90 plus shipping and handling. Watch ebay, cl, OldMiniBikes for used ones.
As I understand it, the Raptor carb is your basic 5hp Briggs FH carb. I don't know if the Raptor is like the Briggs Fun Power with wider mounting holes in the block, if not stay away from the Fun Power carbs. I have some older 5hp tiller engines and the Fun Power carbs will not mount up to them, mounting hole spacing is different. The block is not the issue (has 3 holes to mount both types of carbs) however, the carb will only mount to the wider mounting holes, which many old blocks don't have.
If you are running gas, maybe don't want one used for kart racing, they are modified to run methanol.