Thanks Rusty and Poppy.
I managed to get someone down to $40. But that is the lowest I can find for blasting after calling around a dozen people.
I'm now considering getting a reconditioned drum for $60. They tell me that the reconditioning process includes burning and blasting it. And they claim there there are no liners or rust inhibitors sprayed inside the drum. Do you guys know if this is the common reconditioning process? I'm actually surprised that it would come out with a bare metal interior.