I wanted to add that setting up a vivarium shouldn't cost a great deal since you already have the tanks. Some substrate, a few plants, and a small filter if you set up a pond area. You can get a Whisper internal filter for around $10-$15. They are made so only the bottom has to be submerged. Soil can be gotten at a Dollar Store. Just check to make sure it doesn't have added chemicals. I saw a bag of organic seed starting mix for $2 at my local store. Most stores have 4-6 packs of plants for around $2-$4. Or you could use artificial ones from dollar stores. Most of the snake and amphibian people I talk to do that. There are a lot of websites with instructions to make your own rock formations out of Styrofoam and concrete.Here is a good website with ideas for do it yourself projects. reptile terrarium rock wall background
Poison dart frogs are so cute. I want some of the mini bumble bee ones. I, too, was surprised to find that they aren't poisonous in captivity. It is a type of insect that they eat in the wild that makes them poison.