So, I went to Petco to get the foster gerbils some food, and I found the following on clearance:
Free-standing water-bottle holders: $1.48 each.
3-pack of "Nature's toothbrush" pine cones: $0.50 each.
Two-piece (large) natural wood tunnel (the kind that you can put together in a "T" shape): $2.18 per set
Just wanted to let you all know!