Blue reptiles

[rubbertoes]

So i am doing a project for my school, where the principal said i could keep any reptile in the school (nonvenomous) as long as it could fit in a 50 gallon long tank which the school provided, and is blue, our school color. I would like to keep the price fairly low, maybe no more than a couple hundred usd. I am planning on starting a fundraiser or trying to recieve a grant of some kind. Any suggestions? Amphibians are ok too.

Edit: it also must be fairly hardy, because i will not be with it at all times. It will be brought home on long breaks. I was thinking of like a blue strip garter or puget sound. or poison dart frogs.