They just need a properly-organized fundraiser. Bigger than a bake-sale, though...
I've got it! They can sell fully-automatic weapons and destructive devices for less-than-NFA prices to the 'inactive reserve' of the Oklahoma state militia! And make clear that, because of Oklahoma's central strategic location in the US and manpower requirements, make it so those 'inactive reserve' positions in the militia are assigned to any citizen in the United States, just to ensure a ready reaction force for the state in case of emergency.
Wham-bam, training budget acquired!