Some things I have been able to get a gobbler to shock gobble include slamming a car door, bellering YEEEEHAAAAWWWWW! at the top of my lungs, banging a pot lid with a stick, a cell phone ringing, and a buddy claims he got one to gobble when he cut a particularly wet fart.
By it's very name, anything that is a little "shocking" will get an answer. They famously blow it out when a thunderstorm is brewing up on the horizon and the thunder rolls. Just don't do a lot of it.
For purchased calls, crow calls, coyote imatators, and peacock calls are pretty reliable. Call for a gobble. Move sideways 20 yds, call again. Triangulate and shut the heck up! I've had guys come marching thru the woods like a trombone player in a marching band hooting on a locator call. All the while I had to listen to the particular gobbler walking awa just as fast as the idiot was approaching.
Save your money and google "barred owl call" and rehearse it until you got it down pat. It's not that hard to get the rhythm down. Don't matter if you don't have barred owls in your area, it's genetically imprinted into them to answer. We have great horned owls and gobblers ignore them.
As for calling them in after locating, I use home made slate calls, box calls, wingbone suction calls, and my voice. Once they are close, I drop everything and just use my voice to duplicate the purrs, churrs, pops, and little giggles they make when feeding. Sometimes a gobbler gets really peeved when that hot hen that was so very responsive now decides she is more interested in feeding than breeding!!!
