Check out here.

http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR3.T RC2.A0.H0.Xbmw+diamond+key&_nkw=bmw+diamond+key&_s acat=0

It is possible to repair the keys as I repaired both of the e39 keys but you need a good soldering Iron and very steady hand to swap the transponder chips.

Easiest option is to do what I said.