Definitely taking a chance.
Please correct my naivete.
To get decent schoirah, the moicher needs to also take shvache stuff, which he can't necessarily sell, or at least needs to put in a huge effort to do so.
He shvitzes for a month, between ordering, setting up shop, hiring and supervising workers, and selling.
A certain percentage of his inventory will be passul.
It's seasonal, so his profit can't merely be 1/12th of his living expenses.
Bottom line: the most successful esrog merchant I know is a pauper (he is a full time rebbe).
Perhaps the growers and wholesalers are raking it in, but I have rachamanus on the retailers.