If you are looking for an electronic caller. The Foxpro is probably the most popular.
There are a ton of mouth blown calls on the market,most of them are fairly cheap.
If you buy one and don't like it go buy something else.
The main thing is call where there are some predators or you will get bored and lose interest.
If your in the right place when you blow that call,hang on because you will be hooked.
L.P. is right on the Foxpro, I haven't yet convinced myself to spend $400-500 on one though. I've used dozens of different mouth calls and most will work when used properly in the right area. My top 3 picks would have to be the Sceery(semi-closed reed), Circe made by Lohman(closed reed) and Tally Ho(open Reed). Go to www.allpredatorcalls.com they have a lot to choose from.
I run a fox pro CS24 for a electronic call which is amazing for the output. Couple a fox pro with a good decoy and it is hard to beat. For hand calls I made my own and you can buy Mylar and sound boards in so inclined. For production calls the critter calls standard is a great all around call. You can find a ton of custom calls on predator masters as well.