I agree with keeping dubias as a staple, they're the best blend of healthy and easy to breed. Just make sure your cham will eat them before you go buying a colony!
I'm SURE there are people in Houston with bugs to trade. If there aren't any on here then it wouldn't hurt to check gecko, tarantula, dart frog, and other forums based around insectivores. As was already mentioned you can check out craigslist, there are usually some ads floating around my local one. I also put up a flier to sell dubias at my local petstore so that's another option. If you're buying online then I would highly recommend josh's frogs, I've used them and I know a lot of other people who have as well. I've also had good luck with mulberry farms.