Where does one find a prosthetic penis?
For a prosthetic that you can pee with, Mango Products makes a “pack & pee” that is a soft packer with a stand-to-pee-device built in. I believe it is around $60.00, so not cheap, but definitely not way out of your price range (unless you have a very, very old/inexpensive car!). They also sell other prosthetics and accessories so that if you do become interested in using it for more sexual purposes later on, you can.