2nd hand parts obviously!
I'm not sure that one can 'shop around'.
One angle that I looked at previously was:
Person without health insurance, and limited means to pay privately. To get a hip replacement as a public patient, there are a few steps, and a delay at each one:
1. Your GP refers you.
2. Eventually you get x-ray appointment.
3. Then there's a waiting period to see the consultant.
4. Once you've seen the consultant, you're then in the waiting list for operation.
What we had looked into doing was presenting to consultant as a private patient to speed up steps 1-3 above, but then going back to the public system.
Ultimately, this wasn't followed in the case I was looking at, so I'm not sure whether or not it would have been any benefit.
It won't make much difference, paying the private fees for an xray and Consultant is the easy part.
The current waiting time for public health joint replacement will prob be years long after the turmoil of Covid.