Sad stuff...

[ponokareefer]

"I guess one starts with the fish and corals, then LR, then the equipment, right?"

This would be your best order, unless you can get someone to take the entire systems off your hands, which would be the easiest by far.

"As well, if no one wants some stuff, what can I do with it? I could never flush a living fish, or throw out live rock (that stuff’s not cheap!)."

You could check with a local LFS to see if they would give you anything for it if no one wants what you have. What are the systems that you are going to be selling?