I paid $775 with a front drive rebuild (port alone is $395 right now) for my Stage 6 last Feb. I got about a 40-45hp bump. Got almost 10k on it right now and its been issue free and whines so much louder. For what you get out of a port on the Eaton, its on par for the money you spent. I am though a proponent though of going right to a TVS though, if you haven't done any mods to the car. The power increase from the port will be become rather tame soon. But its definitely worth it if you want a small bump in power.
ALSO, you should consider buying a POSI port if you can locate one for sale. That's another outstanding port that performs in the same neighborhood as the stage 6. Because of the cult following of that port, a used one could have a noticeable price difference from the stage 6.
I would've been all over that deal going on right now but I'm down to just the Cobra at the moment, due to other circumstances, so I can't afford to have it down right now. I'm installing a nitrous kit so that plus a stage 6 would've been tits!!