This is something that I have been looking into myself lately, but I must say that I haven't really found a great deal of information. From the reading that I have done, I would think that a lot of the Beetle species that are available to insect collectors and the like are probably too hard bodied for many lizards. It is the larger more showy species like Stag and Rhino Beetles that are available and I wouldn't want to feed them to anything but the largest Varanus that I keep, and even then the cost of many individual beetles would make it a cost-prohibitive excercise.
Other, more soft- bodied beetle species that would make suitable feeders aren't commercially available. Weevils would seem like a good choice, but even the largest species, around 25mm, might be a little too small for what you want. Other soft-bodied species, include predatory species that feed on minute foods like aphids and I think would be difficult to rear becaue of their diet. Maybe try contacting the Entomological Department at a local University, to see if they can help you to identify suitable species in your area, and then you could try collectiong aphids and similiar species to feed them during the warmer months of the year.
Despite the lack of suitable feeder species available, there are a number of products available to insect-collectors that might be of use to you if you can catch some beetle species locally. These include Beetle Jelly to increase egg production of breeding females and, various products that are designed to make harwoods rot at a faster rate to the point which they are suitable to feed to wood feeding grubs and beetles much more quickly. If you can catch some beetles locally these products might help you to keep and even breed a suitable feeder insect.
One other possible avenue to explore is feeding the larval stage of the beetles to your herps. Various Pachodna sp. are available here in Europe and they are fat-bodied worms reaching up to 2 inches in length and so make a substantial meal. They also bite harder than you'd believe so watch your fingers ( I know this from personal experience.) You can buy a fermented wood fibre substrate material as food for these worms, this is their natural diet and is very rich in lignans which make them very nutritious for your lizards.
You could also try Googling "Beetle Breeding" or "Beetle Breeding Supplies" and you should find shops selling the products I've described, as well as breeders/ collectors who might be able to help you locate a Bettle suited to what you want. Beetle Breeding is big business in Oriental countries so if you're fluent in Chinese or Japanese, or know how to use Google Translate, you might be able to find a much wider variety of Insects and Supplies if you still want to find a suitable feeder Beetle.
I hope this is of at least some assistance or interest to you.
Kindest regards,
Alex