Luke,
I would approach with a bit of caution. A 1800 could be at least 27 years old and Colchester's wear out just as any other machine tool. If it's had a hard life it's fit for scrap, a good one would make a nice purchase though. It all depends on price, condition and what you want to make with it.
Of the two models mentioned, buy the one in the best condition.
If you need spares from 600 Group they are VERY expensive.
If you can get the serial number 600 Group should be able to tell you how old it is, a good dealer may well have done this for you.
Cheers
John
Edited By elanman on 02/03/2013 16:09:47