LOL That's what makes me laugh, nmr509, is that copies of Madden are mint/complete, but every other game they sell is some generic case/no artwork/missing manual piece of crap.
It's like Madden players actually cherish their games enough to take care of them.
And, as the rest have said, simply buy cheap used games or Jampacks and swap out those cases for the crap ones you received.
OR
If you know someone who works @ Blockbuster, most times they toss out the PS2 cases after putting multiple copies of rental games out on the floor with the case from ONE or two of them. So, ask there too, since you'll be saving them some dumpster space and getting some free cases(perhaps).