Thanks for the info Rockdrill. Lovely guns and not too out of reach price wise, definitely worth collecting.In terms of performance the only realistic area more modern pcp's score over the older guns is number of shots per fill - but to be honest compressed air is the cheapest element of this game.
I would without doubt say the overall build quality is superior. Finish is generally better as well - take for instance the old Daystates proper high quality bluing not this crappy looking paint I have seen on their latest offerings.
As to maintenance - the old pcp's rely on seals just the same as the modern guns, I wouldn't say they need more maintenance than modern guns - certainly not compared to some of the tales told in the general airgun section. For the most part the seal are relatively cheap and easy to obtain, some are a bit harder to find but not a massive problem. Some such as the GC2's are expensive for factory servicing, but they seem to last a long time between services so that isn't so much of an issue really. Most of the major components on the older guns don't wear out anyway.
Price wise, I paid £1000 for the stainless GC2, the other GC2's were between £400 and £600. The Ripleys were between £450 and £500, Airstream just over £600. Daystates - cheapest one cost me £40 (for the Mk1 Huntsman sporter) up to around £250 for the ones shown here.