I have found lots of good vines from the dollar store.
I have a piece of wood from the firewood pile that I cooked at 450 degrees for 20 minutes.
I have sticks that I found in my yard.
I have chunks of coral from the beach that I boiled.
I have large jagged rocks from the creek at my grandmothers house that I boiled that the crumbs climb on.
I have a brick and a half (a full red one with the 3 holes and half of o e giving me another hole) that the crabs climb on and hide in.
I have some plastic wire baskets from the dollar store also held up by suction from the dollar store.
You can use a shallow plastic container like a ziploc or glad container for food and/or water. My local dollar stores sell packs of 5 containers that about an inch deep.
I also found some cool aqarium decorations that are climbable at local thrift stores an the flea market. I boiled the decorations.
Take an old plastic container like what country crock and sour cream and similar containers and rinse thoroughly. Then carefully cut a large opening from the top. Burn the edges with a lighter, flip upside down and instant
hidey! You can do the same with platic party cups by usingthe bottom inch or so and burning with a lighter to make a bowl. We did this when we got our crabs at Myrtle beach but did not buy any of the expensive bowls at the store.
A piece of PVC pipe can be used as a tunnel. My lowes sells it cheap.
You can look around dollar stores, walmarts, thrift stores, craft stores, and hardware stores for inspiration for decorations.