He's one of them. He doesn't need to be bought.
billionaires are not some monolithic group with some secret society where they all meet and anoint one of them like trump to represent them.
There's no need for coordination. Rich people have many of the same interests. They include the ability to hire anyone they want and buy the materials they want at the lowest possible cost, and low taxes. Trump obviously has additional specialized interests and would benefit, as president, from issuing executive orders sticking it to his competition and making it easier for Trump-related companies to get financing, acquire property and so on. Just because Trump says certain things this year, which are different from what he said last year, which are different from... is no reason to make him the GOP nominee.
By golly, you've convinced me!
Just because Cruz says certain things this year, which are different from what he said last year, which are different from... is no reason to make him the GOP nominee.
After all, Cruz's wife works for Goldman Sachs, the Richie Rich "investment" firm, and it could be that Goldman Sachs needs another Jon Corzine type in a position of power.