As it turned out in my experience, you don't have to spend the extra money for a "mated pair" when buying a Shrimp Goby, and a
Pistol shrimp. When we purchased our first "pair" the Goby was DOA, but the shrimp handled the shipping okay. The online store sent another Goby, and the two paired up within seconds.
After remaining in my 30 hex for about six months, I was attempting to reaquascape, and must have trapped the shrimp under the sand because he just disappeared. Then the Goby stopped eating. I figured he was stressed by losing not only his partner, but his burrow home as well.
Considering the fact that the Goby would waste away if I didn't do something quick... I bought another shrimp. This time, a
Tiger Pistol (the last one had been just a plain Alpheus). Well, it took all of two seconds for the pistol shrimp to find the Randalli Goby, and he immediately went to burrowing right under the Goby! Today they seem like they've been together forever... with the goby on "lookout," never more than a few centimeters from the shrimp.
Just thought I'd share our success story with our symbiotic pair. I know that several have asked if just any shrimp would pair-up with just any goby... and luckily, it happened for us not once, but twice! If you're considering buying the "pair," I'd suggest not spending the extra $50, and buy them individually. Just make sure that you do a little research, and purchase the right family, as all shrimp, and all Goby's don't necessarily team up.
Here is a photo of our last Pistol shrimp. May he RIP!
Hopefully, they can stay in business charging the lower prices!
I'll try to get a shot of the new Tiger Shrimp. He's very pretty. Maybe I can get him to stop building long enough to say cheeeez. :santa: 
