Will you be housing it in a heated room, or will you need to raise ambient temps too?

I have never kept GTP, but many crested gecko people like these tubs. It would need some modification (branches, heat tape or similar on the back, etc.) but might work for a GTP. I believe I've heard 2x2x2 as a minimum enclosure size for GTPs.

I'd just go to target or another store and look for a plastic tub that's at least 2x2x2 with a latching lid, then install perches, heat tape (possibly on the side... Not sure how arboreal people use heat tape) or plan on a heat lamp on a stand to hang above the lid of the tub to raise ambient temps.