I get the blades for my saw at HF also, I think around $6 for a pack of 5. They are a VERY fine tooth design, when cutting through just glass, they last a LONG time, obviously, throw in some decent thickness wood coring...not so long.
But, considering the amount of holes I put in boat (

), and considering the last pack of blades I picked up maybe 4 months ago, I'd say I'm doing pretty good. And I still have 2 unused ones left...
BTW, with patience, those blades will even cut through a 1/2" SS bolt. Ask me how I know... :x :x