I think you can buy shell tops (minus the fans, lights, ballasts, etc) from either the mfr, nanocustoms.com, or nanotuners.com.
People buy them to do DIY upgrades to their tanks.
I'm in the same boat. The feeding lid clip broke on mine (1st day) so I need to get a new one as well. I've e-mailed JBJ but have yet to hear back from them on replacement parts.
Good Luck