i dont know how big your set up is... but my 2 are only in a 5 gallon (thats a diagonal pattern) and were currently using a beta heater since regular reptile/amphibian heaters were too big. remember the whole thing has to be under for some heaters, or the beta ones have a fill to line.... SO moral is... even if you dont find one with the term REPTILE HEATER, even specific fish ones will be ok... i paid 15 bucks for mine from petsmart

but i believe our local walmart also carries them for 10 something... it was too big for my tank!

good luck!