Posting a 360 wireless racing wheel - postage price question

I'm selling my official wireless racing wheel for 360. I have no idea how much to put for postage. Anyone got any idea how much I should charge and some suggestions as to who I should go with?

The post office were charging between 15 and 20 quid depending on the cover I needed. I noticed most people on eBay were charging £5.50. I don't understand how they can post it so cheaply.

how heavy is it ??? there must be rough weight guide on the post office site...

http://sg.royalmail.com/portal/rm/Price ... r_redirect