Some of the hides ive used ....
Old cardboard boxes ... good for about a week.
Cardboard tubing from carpet rolls ... can cut one roll up into alot of 18" pieces ... throw away when they start to smell. (BTW you can usually get the tube for free).
Pet Igloos ... not to expensive, last for a long time ... dishwasher safe.
Shredded paper ... Long strips ... heap em up in a corner ... theyll make their own hide.
The Igloos are probably my favorite as they are cheap, easy to clean, and store well. Followed by boxes, they seem to like old kleenex boxes, baggie boxes, and shipping boxes. On larger boxes they like to have an extra escape hole.
Cardboard will soak up urine and smells from the cages ... so while cheap you go through alot of them.
The only enclosures that get cardboard tubes now are my mouse hopper ones. They get used to hiding in paper towel rolls, so all you have to do is cover both ends to move them (like when cleaning cages).
Bryan