Ha, no thanks. It took me over an hour to just lightly skim this thread. (a fasinating thread, or no way would I have spent that amount of time)
No telling how long it'd take to fully read through all ~1,500 posts, stop when hardware, fish, coral, elec. specs, lights, etc..etc. are called out,,, look them up,, then cost them..... maybe when I retire.
I absolutely love the work Goodwin has done with this thread and project, and offer sincere kudo's for sharing it with the viewing public... but the question stands. We can have fun with it, or dismiss it, Goodwin's call to decide if he want's to offer an estimated net or not... I just thought it'd be fun to inject a lil' mini-contest into the mix.
My 20k estimate comes from what I've been told by other folks who maintain salt water aquariums.. .. that the cost tends to be exponential as you go up in size rather than linear. Since I've probably dumped at least 2k into my 75g, I actually thought the 20k estimate would be light..... but I could be wrong.