I got mine from www.yourcablestore.com for $5.95 USD shipped to Canada. I think I used their ebay storefront though, and not their website to get it. Excellent experience, and they gave me a $1.00 coupon to apply to my next order. Any takers on the coupon code? I doubt I'll need to get another one anytime soon.

EDIT - Taking a line from Mara, I too am not affiliated in anyway with the store I am recommending for the USB adapter. Just relating my experience using them, and I have this discount code I won't use - so just tying to help out someone else!