It matters what size they are. I don't see why the large critter carrier would not be big enough for a dozen gray tree frogs until they get to the size of 3/4 to 1 inch.
If you have a lot of froglets, you should separate them according to size anyway. I think that keeping them and high numbers would be to their detriment.
It is true that they cost a lot, but keep in mind that they come with a lid that you do not have to worry about metal contamination. See the Amphibian Medicine and Captive Husbandry Book, where he discusses several times about sources of metal contamination from lids.
The reason why I like the plastic containers is that they are lighter, and easier to clean. The BIGGEST advantage is the little trap door in the middle of the lid that allows you to move the froglets are back and forth without worry of them escaping. Try to get that at the 10 gallon!
>>Do they sell critter keepers large enough for grey tree frogs? The biggest one I've ever seen is an 8-gallon, although I'm sure they're available larger than that. However, they're probably better off getting a large tank than a bunch of critter keepers, I think, because an 8-gallon critter keeper costs about the same as a 10-gallon glass tank, with lid.
>>
>>
BTW, Bordercollie--GTF *usually* connotes it's a green tree frog, probably because they're better known.)
-----
*Humans aren't the only species on earth... we just act like it.
".the oldest task in human history: to live on a piece of land without
spoiling it."
Aldo Leopold (1938)