I bought them a while ago.
I think they cost around $16 each at the time.
I bought 23x31”.
I had them stacked 31” high and them stood frames up inside. This made the shipping a lot cheaper,
You can work out how many frames you can pack like this and order accordingly.
I have a MHM and I add my own registration pins. I think today they sell they with pins welded on.
Might we worth checking.