Martin, I just browsed around for those yesterday, and there are a couple of places that sell full sets for a touch less than $1/bolt. I don't recall where that was though. I think you may just have to pay the piper. I haven't found anywhere that sells them for less. Even my go-to hardware spot (McMaster-Carr) doesn't have them.
On the other hand, I just saw that Brother's truck sells a set of 20 for $79 and it didn't even say they were stainless.
