What would I do?
Never take on an animal that I don't plan to keep, or respectfully re-home. If I do rehab or catch/release, I follow strict guidelines, involving NEVER mixing wild and "captive" or "pet trade" creatures. If any animal becomes sick, deformed or disabled, it is treated by a professional (and given a clean bill of health) or it is not released at all.

In the case of the tadpoles I have (10-ish toads, 4 ranids)?
I've taken on a small enough number to either care for all of them myself, or offer them to other local keepers with a similar level of dedication. I would suggest that you contact local REPTILE-specific stores (if you have them) and tell them that you may have excess (XYZ breed) toadlets, which you are looking to ethically re-home. If they aren't willing to pay, ask if they're willing to trade for crickets/supplies. If they aren't willing to do store credit, offer them for free. Offer the same deal/s to local keepers.

Here's the other thing: Some people don't care, and irresponsibly contaminate the environment. It's horrible, it happens on a daily basis, and sometimes does enough damage to really get some guts in a twist (re: snakehead, piranha, introduction of malaria). It's up to each person to decide if they wanna be a "good guy" or a "bad guy" or a "chaotic neutral" guy. Ask for advice, follow it, don't follow it - it's ultimately on you.