A while back I submitted a post to see if anyone had any bright ideas about obtaining new/spare keys that were a bity more reasonable than my local dealer's quote of "about $850".
Jusy thought some might be interested in my experience with a supplier found on Ebay, listed as "carolyncbishop" based in Tintenbar, NSW (not a place you'd expect a major commercial enterprise!).
While a bit apprehensive, comments from past customers were almost 100% positive so I thought I'd take a risk. I signed up through Paypal for a genuine BMW factory key for my 330i. After paying, ($378 + postage) I lodged my rego/VIN details and copy of passport through their secure dropbox.
I got an email shortly after confirming receipt of details and advice that the key would be sent by Australia Post Express within 2-3 weeks.
After about 2 weeks I got advice that it had been dispatched and I received it yesterday about 3 weeks after ordering.
As advertised, the key was a genuine part, was fully coded and it worked! From my experience, this supplier provides a good service.