HUGE retirement plans for mega-rich UFC fighter Chael Sonnen, told our source that he wants to buy the WWE when he quits fighting ... a company valued at more than half a BILLION dollars. And Chael's rep insists he's not joking, telling our source, "It is 100% Chael's intent to buy the WWE." In fact, the rep says Chael is already meeting with bigwig friends in the investment world to enact his takeover. Bad news though -- a rep for the WWE tells our source the company ain't for sale ... at least not yet ... so Chael better be prepared to put a sweet offer on the table. The rep adds, "We are a publicly traded company, so [Chael is] more than welcome to purchase shares of WWE stock and become one of our valued shareholders."And that's the bottom line!