first of all, Im sorry to hear that your account was suspended for to much intl traffic. Im sure its a frustrating situation and I hope you find a way to get in YPN again. may I ask whaat amount of Intl traffic you have?
regarding the invitations, I've seen some on eBay. you may want to try that. but in my opinion you are risking to much if you get into the program for a 2nd time with an invite that wasnt sent to you originally. why? because when YPN goes global they will reinstate all the accounts that were suspended for international traffic and if they found out you "cheated" the system and TOS they may terminate your accounts and wont let you in ever again, like they will ban your account for a very long time/
I've heard its not allowed to buy or use invite that were not sent to you originally.
my advise to you is that maybe you should wait until they go out of beta and in the meantime try other program like Adsense or Miva to generate some income.
anyways, good luck and hopefully you will get in YPN soon :)