Frankly, we shouldn't really be surprised by the news. Google's hot release Google+ is currently adding people only through invites, which means the unlucky ones who haven't got an invite are facing a difficult situation.
A section is giving away their Gmail IDs in Twitter and random forums, hoping that some gracious people would drop a Google+ invite -- only to learn that spammers did pick up their Gmail IDs, instead of that gracious Google+ guy. Can you really blame the Google+ hawkers of eBay, if they are cashing in on a perfectly ripe scenario?
The situation is reminiscent of Gmail's reception, when it was launched as an invite only e-mail service. eBay did sell Gmail invites back in 2004 for $200! Gmail, when it was launched, was almost like a Tech medal you can get for being a geek.
Is Google+ playing hard to get? Probably. When Google Buzz was launched, Google made a terrible mistake by forcing every Google account holder to be on Buzz, raising umpteen complaints regarding privacy. Google doesn't generally make the same mistake over and over again.
Sure, Google+ is getting largely positive reviews, but Google+'s sudden popularity has to be attributed to the invite-only strategy. The curiosity Google managed to stir up was much needed for the tech giant whose Achilles' heel is online social networking.