Let's assume the wonderful world of amps was perfect in one regard: there are no stds including no aids and hiv and the girl can't get pregnant.
Assume your favorite provider only perform cbj and cfs. However, she is willing to perform bbbj and bareback full service with an internal discharge for an additional fee.
If you normally tip her $100 for covered services, what is the most addtional tip (if any) you'd be willing to pay for bareback services?