Just bought my 8gb Micro Sd card for my bb pearl 8100, only 22.99, Did i mention it is Sandisk Branded . The seller is "lscollection", they have a 99.7% approval rating so hopefully what they send me is genuine.
If these are anything like when I was searching for Memory Stick Duos for my PSP, 99% of these cards are not legit. That's not to say it won't not work for you though. I was quite happy with my fast, high speed, fake card that I got for a good price.