I've been monitoring these and I see that only three volumes sold for $10 each. Even though you only sold three of them, that means you got $30 back out of the $45+ you spent on the set. If you can sell the other five at $5 each, then you pretty much got all your money back.
Although I must say that it's amazing that not all volumes sold at $10. This just goes to show that this Ultimate set has caused the individual volumes to depreciate significantly.