I just looked them up, on the Eleiko site they are $47. I assume that is for a pair, which would put them around half the price of SBDs. They only have the small sleeves in stock right now, but:
“Please note that we will be releasing a new version of these knee sleeves in the coming months.”
Note: on second glance, they are in fact sold as a pair. That’s pretty fucking cheap, especially considering they are approved by the IPF which makes everything more expensive.