Crenicichla compressiceps are awesome fish. I keep 3 of them in a 55 gallon, and things are going pretty well so far. I've had them for about 2 months. My male is about 3.5 inches, and my 2 females are about 3 inches. My experience with them is that the male runs the show and not the females, but then again I haven't really kept them for too long. I'd have to say that inch for inch, they are one of the most aggressive species I keep! Mine live with a gold severum, a female convict, and a very aggressive firemouth (seriously... this fish is evil incarnate). I also keep 3 yellowtail botia with them. None of the tankmates bother the pikes.
And IMO, $13 is not outrageous for these fish at 2.5 inches. The store I work at charges $14.99 for a 3-3.5 inch fish, so I guess that's a better deal, but it's really pretty comparable.