Actually, SENS-like repair therapies would be mass-produced infusions for the most part. They'd be the same for everyone, a mix of small molecule drugs targeting metabolic waste (amyloids, cross-links, lipofuscin, etc) and gene therapies (allotopic expression of mitochondrial genes). Some replacement of stem cell populations most likely, which would be a tissue sample, send to the clinic, get back cells for injection.

If you look at comparable technologies today, autologous stem cell transplant is the most expensive, and you can get that for a few tens of thousands of dollars via medical tourism. Other points of comparison are, say, biologics for autoimmune conditions, which are enormously finicky to mass-produce at the moment and presently run to a few thousand dollars per shot or infusion. They'll get cheaper. Generic drugs, widely produced and past their legal protections, on the other hand cost a few cents to a few dollars for a dose.

For SENS-like repair technologies you're looking at one treatment every few decades if it's very efficient at clearing damage, or perhaps every few years if it isn't.

That sounds nice, but there are a few problems with it. 1) You can't predict the future, so you don't know that those treatments will work or will actually be inexpensive. 2) Patents, greed, lawyers, etc. 3) Since the treatments don't exist yet, you don't know how often they would need to be done.

Bottom line is that you seem to be awfully confident about predicting the future of things that don't exist yet.