I've got a 15-year old cromoly Trek 830 sitting in the garage. I'm thinking about converting to a single-speed as an excuse to get some much needed bike mechanic practice - of which I have very little. Some quick searching on the web tells me I can buy a conversion kit w/ spacers or could go really cheap-ars and use PVC pipe as a spacer. I am not adverse to cannibalizing the existing cassettes as part of this project. I'm assuming I may have to buy a chain tensioner.
I don't want to put a bunch of money into a bike that isn't worth anything now. But I want a conversion I can ride reliably with the missus, on errands around town, and up the hill at the local landfill turned park. If the conversion kits aren't much, I'd probably do that as I assume they'd be more reliable long term.
Short of putting the bike in the gears of choice and cutting the cables - what's my best bet for a cheap, reliable conversion?