I have the IR pneumatic body saw and I agree, finding blades is a pain (HD only stocks bits/blades for the tools they stock). While there are things at HF I am willing to buy, I'm not sure blades and grinding wheels fit that category.
I think I usually end up buying them online. Search for IR blades. They have them in 5 packs, I think, in 3 different Teeth Per Inch.
Someone here on GJ turned me onto Sterling blades for this saw (don't remember who, but THANKS) and was kind enough to send me a couple to try. I like them and they are a decent price (in bulk) from here:
http://www.jandrweldingsupply.com/store/Sterling/Menu.html
Since I clearly have the saw, I don't mind buying in bulk, but have not yet.
Kev