i've got a complete conversion kit if you want to make a go of a former geared bike. it's a lot cheaper to ship from the USA too!
spot brand spacer kit...a series of spacers to take up all the extra space on the cassette. various thicknesses make dialing in the chainline easy.
several cogs...16t king alloy cog (essentially new), 17t endless alloy cog (used, perfectly serviceable), 20t steel surly (essentially new)
rennen tensioner...bolt-on, rock solid. never a problem with chain drops. push-up or push-down. used, perfectly serviceable. replacement bearings included.
PM if interested.