Since you've got $150, why not buy an MM2 (1.5" rollers)? Build your own baseboard and hopper to save the $45. The MDF board they send you is crap.
Do buy it with the 1/2" shaft, much sturdier than the 3/8" one, and the Harbor Freight Heavy Duty Low Speed drill driving it has a 1/2" chuck anyway. It costs $50 or less with the right coupons.
Why do you think a 3-roller mill with give you a better crush than a 2-roller one? My MM-2 does everything I expect it to. I do tweak the gap for the size of the kernels (wheat, rye etc. are smaller than barley) and mill them separately.