There appear to be fewer than 89 units of the M.2 SoM evaluation board (version 1.2). It's not a high volume item, but I don't know the rate they normally sell at.
The expected release date for the updated M.2 eval board is not yet available.
Work is in progress on the replacement for the M.2 SoM eval board, but I don't have a release date.
It looks like there are 14 in stock, which is surprising because I thought there were many more in stock than that. It is possible that a distributor purchased units.