Underworldrob, no offence, but personally as the former number one super fan, i'd not have bought that poster, at anything more than £5-£10, and even then would have thought about it seriously.
Purely and simply because its just a poster of a bug, with Underworld's name on it, its not in an Underworld recognised font, and its pretty insigificant as a piece of memoribillia, even if it is signed by the artist. It has no relevance other than for that specific event, which i suppose unless you went to it - it has even less meaning... almost every other underworld event poster has some recognised UW imagery or fonts
i know its framed but even so - its not worth anywhere near what you are asking, imho
u might be better off selling it via a rare flyers website like this:
http://www.raveflyers.co.uk/prices.htm, because i really don't think any UW fan here will part with more than £10 for that poster, unless i'm sorely mistaken