Hi for silk worms its easy to breed them yourself.
You can buy a batch and let them spin cocoons, than when the moths come out let them lay eggs, each moth will lay about 200-500 eggs about 2 times.
When they layed their eggs you can feed the moths as well to your gliders.
Than the egg care, just putt them in a plastic seal bag in the fridge for about 3 weeks, than you take out some of them to let hatch at room temp. (you can leave the other eggs in the fridge as they stay good for about 5 years!) Its best to let a lot of moths hatch in summer and let them do the egg laying thing in a little screencage outdoors. This way you have plenty of eggs for the rest of the year(s) depending on how many moths you let come out and on how many gliders you have to feed.
another option is to buy the eggs online, same counts for hornworms but they should be fed a special made chow. (which you can buy online as well)
the silk worms just eat mulberry leaves which you can get outdoors.
Waxworms are also easy to breed, you only need some wax paper and pollen.
So for cost efficiency Silk worms will be cheaper and easier to raise than horn worms. Youtube has some instructions on how to if you like.
This way you are always sure you have the best live food for your gliders.