Hornworms are a very big favorite with my guy Darwin. I haven't tried breeding them though since they are an occasional treat. There is some info on this site that may be helpful to you. https://sites.google.com/site/alamocityagama/hornworm-breeding
There is bit of info there, but nothing fulfilling. There is a link for how to keep up a maintenance schedule. But website for link is down. Although, there is a link for a company that sells insects and the hornworms that i may start using. They're about 50% cheaper than what im paying. So thank you for that!
Great Lakes? They are very good. I get my hornworms from them. It's at least a bonus that they are cheaper from that source than what you're paying =).
It was nice when Petco started to carry them. It's good to have a local source, especially during winter. Just double check the containers there as I've seen some of them in less than ideal shape.