I'll talk to my dad. He'd be able to help me brainstorm and build. I'm thinking a Styrofoam option is easiest.
You can get a free styrofoam box from a pharmacy (refrigerated pharmaceuticals are sent in them) or a pet store (tropical fish and plants are sent in them). Possibly a local fish or meat market. Digital thermostats can be bought for around $10-12. Almost everybody has old table lamps that can be repurposed, as well as old picture frames (for the glass). If you do a forced air, you can get a used computer fan and a 12V phone charger. Add some MacGuyver ingenuity and supplies, and you're in business.