For a comprehensive list of all the denominations I like to use Tony Clayton's site; Link Or a direct link to the price lists - Link Be aware that these prices need to be taken with a pinch of salt (I find). Second port of call is searching previous auctions (I like using LCA because it's quick and easy). You can search here for anything you like, just remember the final prices don't include VAT and comission etc. and the bidders will have taken this into account, so the prices might seem slightly lower than usual. Then, if you still need further clarification, check eBay for any finished auctions and you should have a rough idea of price of whatever it is you're looking for. Rarer examples need more digging though as there's less info out there.