I don't know if it has anything to do with how in Mega-baa's shop "615000 yen" = "615 yen" (or something like that), but I think they're making money off converting meta-bugs.
Spoiler for ep 5:
They hadn't actually recovered from the last episode entirely, because I think when Daichi and all were congregating at the stairs and he was asking how much money they had managed to get so far (from converting metabugs as Gachagiri did in the very beginning of the show)... Gachagiri said half a year's otoshidama but if I'm not wrong they still needed in total 12 more otoshidamas to make up for the lost money.
However, they could still function somewhat because (I think) you're allowed to have a negative "balance" in your bank of sorts. If you look at this screenshot...
Gachagiri has -15000 yen in his account. They can have a negative up to a certain amount but any more than that they can't use to repair themselves unless they find more metabugs to make money off.
Normal schoolchildren
shouldn't be having to deal with so much money to pay for their spectacle damage because they shouldn't be getting into this sort of trouble to begin with. If I'm not mistaken, the girl at the start was telling Gachagiri off for accessing the metabug-exchange site which was apparently banned by the school because children have gotten into troublue because of it.