Thanks for the replies but I'm after decent models e.g. if buying Crucial it would have to the the Ballistix range, G.Skill would be FK/Blue, Geil Black Dragon etc etc. The price DDR2 is going for on ebay is actually what made me look at buying new - I'm fairly skeptical of second hand memory/GFX card purchases, who knows how stable they are, what voltage/clock speeds they've been running at for the last 3 years etc, so it'd have to be significantly cheaper than buying new - which it isn't!
Thanks for input, I'll just buy something from one of the usual e-tailors.