That's a good deal, but his lights and most of the equipment are worthless (notice he has a fish only tank, not a reef)... $200 would be worth it for the tank. Even his original asking price would be worth it, but the tank DOES NOT look drilled, so that's a big turn off, IMO. Don't take the substrate -- you don't want crushed coral. From the pics, the rock actually looks like lava rock, which is a no no for reef tanks. They often leach metals, making it hard to keep inverts alive. I would not use lava rock in a reef tank.
That's a lot of fish to add at once, but I think it'd be okay if you make sure you do water changes if anything spikes.
If you already have your tank, then I don't think this is worth it for your particular situation. None of his equipment will be able to sustain a reef tank, his substrate isn't good, and I wouldn't trust that rock. You'd basically be buying the fish. The undergravel filter is useless for saltwater, the Prism protein skimmer is crap, and the canister filter is a nitrate producer... The autofeeders work for flake and pellet foods only, which you shouldn't be using anyways. ;)
It looks like he had a freshwater setup and converted it to saltwater. Somewhat. I take it you don't want the plastic corals and plants? :lol: