In a pseudo-capitalist system like the game currently has (go ahead and make analogies to the Fed printing money to gold buying), you're going to have a lot of people who want to be rich, and a few who are.
But, yes, like Crazed said, it's buy low sell high, and own a shop.
If you have 100 million gold or so, try Arin and Pokin accessory pots with about all of it. You'll pull enough ridiculous things to make it back and more.