FYI, Play It Again sports equipment stores sell free weights for 60 cents a pound. I bought 50 pounds which has been plenty of weight so far.
That having been said, I'm aiming for a Dutch style press, as I don't seem to have the best coordination at stacking weights, and I have to keep an eagle eye on my little press, in the same style as yours, to make sure that the weights don't get off center.