replacement case for 8400

I have a Dimension 8400 3.0GHZ purchased 1 yr ago.  I  opened the case for the first time to install a second hard drive.  I must have broken the tiny plastic "teeth" on the top of the case door, consequently, the case will not shut tightly.  I would like to purchase a new door or the entire case if possible.  After reading several posts on this forum I don't want to attempt to fit the dimension 8400 parts in a non-dell case.

 

Does anyone know where I could purchase a Dell Dimension 8400 case without a power supply?

 

Thanks

DM