Poker, eh? I'm guessing either EOHPoker or SOMER Blink.
There are a few forum members here that play Eveonline that I know off. I personally was able to sell a few PLEX in private deals and had my own thread trying to buy/sell them but the problem is the risk of getting permabanned for violation of CCP's EULA/TOS. As a seller the risk is an account ban and the buyer gets a balance reduction of ISK for the amount of the trade. I gave it up after awhile because CCP is on a "Holy Crusade" to shit in their own Cheerios even though almost the entire gaming industry is heading towards a microtransaction business model and professional gamers will be a reality soon™.
Try sending Luceo a PM, I'm not sure if he's buying atm. His thread is: https://bitcointalk.org/index.php?topic=87176.0
For selling on a regular basis though, you are kind of on your own. ISK sellers usually build up a list of 100-200 trusted customers and communicate via IRC/IM/Skype etc. Keep in mind CCP's "PLEX For Snitches"
reward so sooner or later someone might rat you out.
In my opinion, the risk of getting the banHammer for RMT is probably higher than getting stiffed by someone on this forum.
Good luck and fly safe mate!