How would i find out rough prices for ........

I have recently come into some items related to football and some are special editions etc ...ie items made from materials of Wembly Stadium and some Manchester United products etc and was wondering if anyone could tell me where would be the best places to find out the value of such items before i add them to auction :) :) :) :) :)

depends what they are i can do cards and documents related to football
but some items are hard to put prices on

8) Please don't shoot me down for mentioning another auction site but for price comparison QXL has a lot of footballing lots.