So it's just the little rubber pressure pads you need?
I have a broken PC controller I could get one from if you like, no idea if it'll fit but it's no good to me.
I only kept the controller so my little girl can play with it, keeps her away from my XBox pads!
Alternately it might be an opportunity to stick a better Dpad in there, the Wii Classic controller ones are a little bigger, the Wiimote ones are a little smaller. The knock off ones from HK/China are only a few £ on eBay.