If you can't find the Landmark, here's a link to the Greenhouse Megastore, something I stumbled upon on my way to other things. Seems they sell in qtys of 10 or by the case. You have to click on "option" on each item to see the pricing. Scroll all the way down the page to see the configuration of their various trays. I've not bought from these folks before.
https://www.greenhousemegastore.com/...trays-flats%2f