You can get a £100 voucher for £23 - type in the code EBAY in the discount code screen and jobs a good 'un.
Haven't got my voucher yet (I ordered about 20 minutes ago) but people were saying that they had to wait a godd few hours before it arrived so wont start panicking until tomorrow afternoon!!
I also noticed the 100 pound vouchers on eBay within the same price range. No idea where they get them from, but it seems to work.
Just like I don't ask any questions why the eBay seller I buy my iTunes US vouchers from is from China