Our neighbour just did this. Cost 1500. There are expensive disposal costs.

22:21 here. I don't know about OP, but ours was not empty and our system was broken so the tank was sitting there with oil in it and needed to be removed as we were replacing it was gas.

How much oil could really be spilled if it is already pumped out?

The $1K is the price you pay that it will be done right by someone who is licensed, bonded and insured, and not by others who will do it for free but might spill the oil all over your basement or your yard. Come on, this is not a tough call.

I forget who we used because it's been 6 years, but I *think* the oil company (petro) hauled it off for us. And yes, I do remember well that it was about $1000.

Cross-posting from real estate forum:

We are switching to gas and need to have an above-ground oil tank removed from the basement. Have been told that you can advertise for free on craigslist and people will take it away but after doing some research this seems risky, since spilled oil in the basement or yard can be a mess, not to mention environmental issue. Can anyone recommend a company to do this? We've been quoted $1k which seems high, for something that others will do for free. Any experience with this?