aquariums work fine. if you get one, you will need one with a sliding screen top. if you cant get one with a sliding screen top, you will just have to weigh the lid down with books. humidity can be a problem with screen tops. a quick and effective way to fix that is to cover about 2/3 - 3/4 of the screen with duct tape. there are several people on this site that have done that. if the humidity still isnt high enough you can buy a reptiflo. Will did a review of that product on this site. the only other problem with aquariums is that the snake may feel "insecure". i dont know why people say that...as long as you provide sufficient hides, that wont be a problem.
do you have a pet store near you that deals mainly with reptiles? if you do, you should go there and see what they have for cages. you should definatley find glass cages with sliding screen tops there. but you may also see some vision cages or other like them. they may also have wooden cages, but maybe not. the reptile store near me has kits for you to put them together yourself and already built ones. i dont know if other stores have things liek that or not.
hope i helped ya somehow!