Just got one of these fro Long Eaton Home Bargains. Had at least 20 in stock.
Was unsure wether it would work with later games but can confirm GH World Tour and Band Hero works fine.
They were £10 not to long ago which wasnt bad then but for £3.99 you cant go wrong for a second guitar for those band nights!
It also includes a long USB charging cable.Same as the one you get with a PS3 controller and is long enough to use while playing, unlike the short lead you get with a standard controller. Thes can cost £4 alone!