It's no good to say that somebody bought ammo at some super-cheap price some time ago. Since ammo only goes bang once, all that matters is what you can get it for right now.
Assuming the brass is free and you're willing to shoot whatever bullets you can get at a low price, then it's worth it. Assuming, of course, you're willing to invest your time.
9 MM is, I admit, a little marginal. Assuming you're buying bullets, powder, and primers in large lots to get the best deal, then I think you can almost always make it pay. Granted, it will take you thousands of rounds minimum to pay off the purchase of of the set of dies, so the ROI point is significantly fruther down the road than it is for a 300 mag or something where ammo is $30 or $40 a box.
I reloaded some .308 ammo for a friend and made money back for him the first time I loaded compared to the super-primo stuff he was buying at $28 a box.
Grouse