I'd check with your dealer and make sure the key doesn't require a chip. I learned this little trick last year when I took my GSXR1K on a thousand mile trip to do a couple of track days and realized the key was left on my tool box at home. I called my dealer and ask if I could have a local lock smith make a new key and he said "You are Fooked"! Your bike key must have a chip installed and the only way you'll get a key that works is through Suzuki. However, if you can find a locksmith with proper equipment you can have your ECU reprogrammed to respond to a different chip, but a chip is still required.
So call your dealer and ask if your busa requires a chip in the key? If so, Suzuki is your only option? I don't know when Suzuki began using chips in their keys but my 07 Gixxer requires one!
And,,,,,,,,,,,,,,, I'll bet you can't buy one for $4