I'm trying to lay my hands on a cheap TLR for my brother's wedding next month.
TLR's are a lot of fun but if you need a camera for a wedding next month now is not the time to be purchasing a very old TLR. IMHO, you would think these camera's are so simple nothing could be wrong with them but in my experience most of the complexity has been corralled into the shutter mechanism. As these shutters get old they need periodic maintenance to keep the times accurate. The slow speeds are often way out of whack on the average ebay camera. If you have time and budget a CLA on your ebay purchase you can end up with a nice TLR but I wouldn't go that route if time is short, as it is in your case.
As for prices, go to Keh Camera Brokers and have a look at their inventory and prices. Their condition grades are usually a good indication of where the price breaks are. You can then factor those prices + a possible CLA into what you want to bid on an ebay camera. (I have nothing to do with Keh myself other than I have purchased through them before).