Even a large cardboard box might be better than a fishtank.
I kept my Bacon in a large cardboard box and drilled holes in the wall of the box to put his wheel in and everything and he loved it.
I cut off all the top flaps and cut out a big part of the front wall so that it was more open, and left only a ledge just high enough that he wouldn't climb over and escape. I left the other three walls just as they were.
For the floor, I first put a layer of glossy calendar paper that wouldn't absorb water,
then I layered it with newspaper, then I spread out an old shirt over it.
It was a super cheap way to give him a good temporary cage, and as long as you are diligent about changing out the newspapers and washing the t-shirts, your hedgie should be fine.
Plus, cardboard walls are softer than glass so less risk of getting hurt, and the hedgie will have fun tunneling in the shirt and rustling the newspapers.
It can't be a long-time thing since at some point the cardboard will start to stink since it absorbs smell, but for a temporary cage for like a month or so it works really well.
I'm sure if you go to any big store in your area and ask them if you could have a box they are going to throw away, they'd be happy to help you.