Ok, so you can buy a portable EMP that can impact electronics 1-2M away. Assuming you upped the power source enough to reach that Reaper drone at anywhere from 10k to 50k high, you might be good to go. Of course, you'd probably need a full-sized tractor trailer to haul the power supply.
As for shooting them, if a drone is flying at 100m, yes, it might be vulnerable to small-arms fire. Though, with your shotgun, you'd probably only get one shot before the drone, moving at an average of 200mph, is out of range.
Then again, most drones, at least the ones the public has seen in combat, aren't stupid enough to fly so low.