I am something of an expert on the Scythe, even though I say so myself!
It is still a very competitive car. I still use mine, and it has TQ pace at my local club. I used it at various CWIC and BTCC round this past year and put it in the 13.5 A-final in both series. A few parts are getting worn on it now after 4-and-a-half years of ownership.
Time has caught up with the Scythe in many ways though. It's not LiPo friendly - mine has the LiPo's hanging over the edge of the chassis, the bulkheads are shaped for NiMH. Adapting it to run a reliable gear diff is virtually impossible. And although many of the spares and parts are still available, they are declining.
Whether or not a new-built Scythe is worth £100 is up to you. To put it into perspective, my near-mint Photon with some extra parts only sold for £90 on eBay a year ago (
). Although not everyone's second-hand cars are as well looked after as mine, so you never know what you are getting.