Dang! That's hard core unless they hatched...
OTOH there are some inexpensive solutions that work. In a pinch I've converted cleaned-out margarine or cool-whip tubs over to humid hides. USPS small flat-rate boxes also work, just rip off the tab with the sticky tape. No worries if it gets nasty or wet after a while, toss and replace since they're free.My best advice would be don't waste money trying to take the inexpensive way out. I can't tell you how much I've spent trying to find cheap solutions only to go out and buy the good stuff later. I started out with hides cut from paper bowls. Humidity and spilled water bowls quickly nixed that plan.
QFT.Don't skimp on a thermostat. It really is your most important tool.