its pretty variable since stoot told us there is a possibility that they might not exist forever, my guess is thats because its an item/inventory/ of things all in one and it adds some server strain that ultimately doesnt need to be there.
so, while they are cool and sort of rare (I have some too) its pretty much 'buyer beware' because of the possibility they would just go *poof* at any random moment the TS gods decide its time.