12 Lbs costs about 45$, and was the amount I used for this 5 gallon batch.
With mead, you want to use "raw" honey. That means unpasteurized, with no processing. Filtering is OK, at least as far as I am concerned, but I am sure someone will chime in to correct me.
You should try a small amount of the honey to see if you like the taste. The final product tastes a lot like the honey you use.