Maybe they are $99 because they are stainless steel?

How hard is metal that is "HRC44" as mentioned in the eBay thread?

For the saw to function for a reasonable time they must be fairly hard metal otherwise it would be pointless to include a saw.

How hard is this compared to US military entrenching tools?

I understand there are hardness files that you can use to gauge how hard metals are. How easy are these to use to get a reasonably accurate determination?