Regular Cab $31,045, 2015 F250 MSRP.
Regular Cab $29,440, 2015 F150 MSRP.
Difference of $1605, per Edmunds.
Of course, nobody ends up with the base priced vehicle, but I'm guessing the 250 will require fewer add-ons than the 150 to create a good tow vehicle.
IMHO, 150s are great trucks for everything the average person uses a pickup for, except towing more than light loads. I live in pickup country and see a whole lot more horse trailers, loads of hay, equipment (and campers) being pulled with the 250s and 2500s than with the half-tons. Just say'n.