Hi Alan,
Personally I would try and get a bit more from them than the £160 maybe £200 at least.
Doing a bit of checking fandom is mainly used for science fiction fans.
So in some respects it might be worth a bit more as it does seem a nerdy buzz word.
There are a lot of fandoms around for harry potter, tolkein and a few more.
So maybe even worth more than £200 now if you can get it.
http://www.drwho-online.co.uk/fans/fandom.htm
You might have brought a gem if you can develop it and make it work for you.
You could have a top fandom website listing all the fandoms in the UK, some interesting things you could probaly do if you have the time for it.
Certainly changing my mind on this now, if you can make it work I think this would be worth at least £500 - £1,000 I would sit on it now, try and put up a top sites listing as many fandoms as you can, have links from the sites too your top sites board, make up a little logo like they do for hitwise.
Bit of advertising for sci-fi stuff etc even though most die hard fans will probaly have it on order already as soon as they know something is coming out.
Maybe a message board as well. Certainly a lot of prospects for developing and reselling at a later date when its got a huge membership.
Regards
Mark