You could also give away the game for free for say a month, just to drive up the user base. Then after that you could charge a nominal fee, the idea being that it would then be worth it because you could find a lot of people online to play against.
Was your project originally designed to be player vs. computer, or player vs. player?
Originally it was a trainer, you vs CPU (well, 8 CPUs). And it is still the only bullet point feature I have over the Apple Hold'em, is that this is more along the lines of help-you-learn. The game would track the number of good and bad decisions you make (from a statistical standpoint, not based on the outcome or what the other players actually had). Just to help you play the numbers better.
The problem with running an online service is that its just that, a service. I have a day job (and a very nice one at that) and I cant just stop working for an hour or two to fix the matchmaking and other servers if it goes down. I could hire someone to do that, but people are expensive...