I found the best starting point was to buy a flip-flop hub, built into a rim if possible. This avoids having to mess about converting your existing wheel. You can aim for £50-£100 for that. Then just make sure your BB is tight, re-grease it if you don't know what condition it's in, replace the bearings if they are dump. Apart from that, just get bits and pieces you like the look of. I started with an 80's Peugeot and it was all ebay parts.
I found the best starting point was to buy a flip-flop hub, built into a rim if possible. This avoids having to mess about converting your existing wheel. You can aim for £50-£100 for that. Then just make sure your BB is tight, re-grease it if you don't know what condition it's in, replace the bearings if they are dump. Apart from that, just get bits and pieces you like the look of. I started with an 80's Peugeot and it was all ebay parts.