Well at this price in the UK I think it depends on what sort of warranty you will get with the camera. Robert White is still selling the RD-1s new from stock (although this is also now officially discontinued) for £1462 with a full years warranty. I have seen 'mint' secondhand R-D1's from dealers in the UK at between £850 - £1,000 usually with 3 or 6 months warranty from the dealer.
If its a private sale with no warranty then £1,200 sounds a bit expensive. Given the problems reported in this forum (although my RD-1 has not had any from new in 2.5 years) some sort of warranty would be advisable. In any case new or secondhand you should try to check the camera for some of the most obvious problems reported here before purchase.