I sold my last Plus 8 on the MSCC site and got the fair asking price - you don't have to be a member (I'm not) and it's a cheap way of selling it with less likelihood of tyre kickers as you are with your target audience.
The first response to the advert put down a deposit and came down to see the car the following weekend to collect it having transferred the cash whilst I was doing the DVLA bit.
This was back in 2008 before I discovered TM - the chap that bought the car has only recently sold it on to upgrade to an early Aero.