I did see an ekit card on ebay $5 but that had incoming for free only in 3 or 4 countries. It did have the usa number.
The $20 offer seemed to be a normal card free incoming in many countries.
This is the link to the uk ebay:
International Travel Global SIM Card - call from 49c/m! on eBay (end time 21-Aug-09 16:55:46 BST)