I find buying used chastity gear isn’t going to fly well… Not many people would want a chastity belt that has been worn by someone else for years, due to concerns about hygiene and etc, even if it has been maintained well, many people would’ve think it is not clean because it has been close to someone else’s private parts for long time.
In addition most of chastity gears are made to order, so it may not likely to fit someone else without heavy modification, or unless it is cheap chinese gear. Even brand thighbands or chastity bras are made to order.
But who knows, some might find it not really concerning, so I guess it’s okay.
If I were to buy a chastity gear I’d rather buy new one made to order in my size, so there would be way less issue with fitting, though.