The glass could handle it but it would be difficult to drill such thin glass, but I could do it
The nice thing about the chiller is that it simplifies things, using it would allow you to completely seal off the tank and eliminate the need for an ATO, which no matter what will just be an eyesore on such a small tank. Same with running fans, where would they go??
However before you get too carried away $50 only covers the actual chiller unit, ideally you would still want a controller as well to efficiently control your temp.