@gregda I'm sorry to hear you have further spinal deterioration. The decision on procedures for your L5 S1 must be made only between you and your surgeon. This level must support most of your body weight on your spine and is extremely important. If you have vertebrae slipping at this level, it causes a lot of disability and mobility issues. I think you are beginning to experience some of that.

With Medicare coverage for surgery at Mayo, Mayo will need to answer about costs. Costs also depend on if there is any new imaging or testing required beyond what is current for you. I think that you would only be granted a consult at Mayo if you have insurance that they will accept, and that may be different at the different Mayo campuses. It's good that you have original Medicare. Mayo doesn't accept a lot of the "Advantage" plans, but they have to answer for what insurance they do accept. Your best bet is to call the Mayo department of Insurance and Billing and ask. Here is a link to their office.
https://www.mayoclinic.org/billing-insurance