I saw a gas station with lots of "DEMO" signs spray painted on it, and there are lots of cool light fixtures there. Who should I contact?

Is there anyone working there ? if so I would just walk over and talk to them, beer works wonders in trade,  if not is there any other signs, I don't know what the laws are like there, but up here they have to identify the site supervisor and normally they post a phone number to call, I would call it up and ask them if they are willing to sell any scrap items.. 

There's nobody there, and I don't remember seeing any signs. Also, it's a Shell station.

I'd judge how much you actually want them... if you really want them and all else fails... DO the Ninja lmfaooo

Has it been fenced off yet?
Usually once a chain-link fence goes up around a building, you know the demo is not far off...
(sometimes there'll even be a sign with company name & phone number)

Contact the company who own the station, and ask if they can let you have some items from it.

Contact the company who own the station, and ask if they can let you have some items from it.

That's the best course of action. Whatever you do, don't just take anything, that's theft and will get you into heaps of trouble if you're caught.

I used to work for Imperial Oil ( Aka Exxon, Esso and few others ) and they are almost impossible to obtain used items from surplus, I've taken sledgehammers to computers, cutting torches to anything metal and run over buildings with a cat, even items like steel pipe they wouldn't let you buy them, they are deathly afraid of anything that can somehow, even perceivably become a liability, and I know that your thinking it's a light, but there lawyer is thinking it's an electrocution hazard, or maybe an explosion hazard, or a burn hazard, hence Liability.. (really that is how they think.)

Your best bet is to talk to anyone on the site, or second best call Shell and tell them your interested in leasing the site and ask them to put you in contact with the owner, that might annoy them but it works to get in contact with them, and then again they might be ok if they make a few bucks, on something they are only going to toss out, and who knows they might let you take everything because they don't have to pay you, seriously I've seen that happen the guy got all the copper, panels, lights, and everything they could sell as scrap and all they had to do in trade was take care of the grass cutting to get the city of there back, which they did and then they sprayed it with roundup so they didn't have to return and cut it again..

And if you get lucky and find a worker, really beer works wonders in trade, I've seen lots of things that didn't make it to the dumpster, or get run over by a cat from doors, pipe, metering equipment, full electrical panels, lighting, fridges, pumps, motors, switch gear...

I sent an email to who I think is the owner, now I have to wait for a response.