I know you real want to do this without a power supply and that's probably why you haven't actually done much searching on the bay but IMHO it's silly to do it the way you're planning you loose to much stuff for no gain.
http://www.ebay.com/itm/ePower-EP-4...949?pt=LH_DefaultDomain_0&hash=item3aa4678565
http://www.ebay.com/itm/ePower-EP-4...949?pt=LH_DefaultDomain_0&hash=item3aa4678565