Crickets are very easy to raise and so are pill bugs. You can get a can of good quality venison (dog food) Wellness is only 1.99) and mix that with some cut up veggies, fruit, and greens and turtle pellets. Dandelion and Plantain are very good weeds to cut up and put in the mix. I make a big mix and keep it in the coolest part of the refrigerator and it lasts for a week.
When you go to the supermarket, go to the section that sells the old foods, sometimes known as the "Managers special", and buy those. It's basically old food that's still edible, and the turtles love it.
I use Organix dog food. I also have a sam's club and bj's membership. I raise mealworms and have just started a bsf colony. I also go bug hunting in my study area. It has helped me t id some of the foods they eat in the wild. Also maybe try raising mushrooms like oyster mushrooms.