You may just want to stop by a boutique near you and try them out. I recently bought my first H belt with the reversible strap. I went in wanting a different leather w/silver buckle, but walk out with a gold buckle instead. Since I have bags with both HW, I may eventually get a silver buckle later.
In regards to your questions, I would say that you may be able to find a used one, but make sure you know the correct size. BTW, you may be 70 or 75 cm, just from your info above, but like I say, it's best to try it out in the store. Godd-luck!!