Blimey, I don't look on this thread for a couple of days and there's a full page to get through! Nice pair of bikes there James, I rented a Fuel at Coed-y-Brenin last year and it was very nice.
For your budget second hand, it should be quite hard to go wrong with the big names. What size frame are you looking for?
Pinkbike is good for second hand bikes: http://www.pinkbike.com/buysell/?region=5&countryid=193