If you are willing to pay a little extra to get exactly what will work for you they are sooooooooo worth it!! If you are going to be drilling glass, look for bits on ebay. I think I was paying almost $10 a hole for a glass shop to drill them for me before I got smart and started doing my own! Also make sure the glass shop "Knocks off the edge" so they aren't sharp!
Your custom made tanks made me think of these! I used to work in a candy shop. Cheap ass option maybe? Maybe not quite as ff proof, though. But I'm sure I can work my way around that. These could work as grow up tanks for thumbs maybe.