In my experience, any cylinder you are looking for is scarce or terribly priced.
Over time most of these extra cylinders from convertible revolvers get separated from where the gun is kept/stored and after grampa gets forgetful (oh, me) or dies hardly anybody knows where they are or what goes with what. A local gunshow dealer offered me a whole $5 each for two extra 22LR cyl.s (what most people want) I had on my table for $20 ea. For that I kept them..........BTW, they are gold if he has them for sale.
Send me some detailed pics of what you need and we'll see if they match at all.