I have the calls mentioned in my possession, and am a huge fan of guys like Mr. Al Shoemaker and Mr. Marlin, but what about a Liberty< Mississippi era made Lynch World Champion box call which can be bought for around 30-35 dollars on Ebay regularly? Yes, you may have to buy a couple to get one that has a very realistic gobbler yelp, but 30 dollars a pop is still way under what these other boxcalls will cost. And, if you have to buy several to get one with a really good gobbler yelp on it, you can resale the ones that you choose not to keep for close to what you paid for them on Ebay to guys who maybe just want them for the hen yelp on the other side of the call, etc.
Even with these higher dollar custom long box calls sitting in my office, when I want to talk to a gobbler, a well tuned Lynch World Champion is hard to beat for a good gobbler yelp. Also, the Roger Parks gobbler pot is also a better buy if you want to save a dollar over these higher dollar long boxes that others mentioned. You can get the same result either way, just trying to maybe save you a dollar or two.