Soundsmith does offer an A90 retip using what Peter told me is the Ortofon Replicant 100 stylus. He has them in stock. It is a stylus-only retip, affixing the diamond to the original A90 cantilever. Peter does it personally. I don't recall the cost--around $500, I believe. I had him do mine and it sounds as good as new.
Before Soundsmith, on the same cartridge, I had Orotofon perform their full rebuild/retip at $1,800 (yes, I've logged many hours on this cart) and Peter's sounds just as good. The only difference is that I now keep the arm parallel rather than significantly raised in the back, so he might have changed the SRA from factory. I don't mind that change.
Before Soundsmith, on the same cartridge, I had Orotofon perform their full rebuild/retip at $1,800 (yes, I've logged many hours on this cart) and Peter's sounds just as good. The only difference is that I now keep the arm parallel rather than significantly raised in the back, so he might have changed the SRA from factory. I don't mind that change.