That's expensive because Home Depot is expensive.
I can get OC R38 for almost half of the price that Home Depot charges.
If they are 4x6 sheets, that's about $0.42 per square foot for 1/2" 703.
The last quote I got through Kamco for 2" 703 was $0.94 per square foot.
I know everybody wishes that they could get all the fiberglass that they can carry at the Home Depot, but the reality is that if you could, you would be paying up the nose for it.
You're better off just looking around.