I picked up
this set of o-rings off ebay a little while ago.
The best thing I have to compare them to
are these o-rings I got of massdrop a year or 2 ago.
Size wise, they're the same at 1.5mm thick. No clue on the hardness of the ebay ones. The massdrop ones were listed at a hardness of 50A. By comparison, the ebay ones are definitely squishier when compressed lengthwise, so maybe they're softer (someone smarter than me may be able to chime in if those properties have a correlation).
I don't know what all your requirements are, but you may be able to get something similar off ebay for a little cheaper.