Blindjim I had a direct quote but now I can't find it but as I recall it would cost another $150-$170. Depends also on whether you get your own battery charger or have the modifier supply it. Same with the modified USB cable that eliminates the power wire so all power for the M2 comes from the battery pack.
It's hard to know if doubling the cost will double the improvement.
It's hard to know if doubling the cost will double the improvement.