Draggin, buy new, choose your own specification and colours, get the manufacturer's full warranty, treat it well from day one and keep it for ever. For £1,500 you could fly over in the Spring and stay for a few days, see it being built, meet the guys who are making it. What a story to tell your grandchildren.
Chris J
F-Super
Then drive it for 6 months and trade it in on a 4/4

Seriously: if you have been bitten by the bug buy new. The older ones will ultimately all have more problems than the latest model which has most of the problems fixed.
If your not really sure get the cheapest second hand one you can find and if you find you really do like 3 wheeling you could trade up to a new one. Short term on a second hand one you would probably get most of your money back.