If your price is competitive enough for a dealer to buy your a/c, then you can sell instantaneously. Otherwise, if you do it yourself, 2-6 months seems pretty typical a timeframe.
Personally, I'd prefer to leave a bit of meat on the deal for a dealer and move on. If you hold out for top dollar for a year, you can spend £3-5k in insurance and parking alone - let alone annuals, 50 hr checks etc. which can easily equate to 10% of the value of the machine.
David Morris at "Justplanetrading" has always been pretty reliable in my experience. Just don't expect silly money....
Good luck selling!
