This past weekend, I had some help carrying eight 4x8 sheets of type X drywall up a flight of stairs. It was not easy. I know the sheets couldn't have weighed more than 80 lbs, but it felt like they weighed a ton. I need to get more up the same flight, but won't have help this time and I am not keen to paying a few hundred bucks to have it done.
Some research has lead me to the Gorilla Gripper and PanelHandle. I've read that the Gorilla Gripper can damage drywall. Haven't found much else about the PanelHandle. However, the demos I've seen on YouTube show them using it to carry sheets of plywood.
I ended up getting a hand-held panel carrier from Lowe's last week thinking it would help. It goes under the sheet and you lift it with your right hand and hold the top of the sheet with your left (or the other way around). It turned out not to help at all.
I really like the Gorilla Gripper provided that it doesn't damage drywall.