Who pays for stunt casting?

Last Friday Questions before Thanksgiving.

Derek (in Calgary) starts us off:

My question relates to stunt-casting and the fee paid to the stunt-casted actors.

Suppose you are running Modern Family and for whatever reason you decide to offer a small one-episode cameo role to (say) a well-known baseball player. How is it determined how much the baseball player is paid? Is it the same rate as