StreetEasy active listing scrapper by building.
Assuming the url of the building you're interested in is: http://streeteasy.com/building/200-e-62
.
Here is the query you can perform:
ExStreetEasy.BuildingScrapper.fetch("200-e-62")
# => [[id: "1180890", address: "#27E - 200 East 62nd Street", price: "$6,250,000"],
# => [id: "1180566", address: "#12D - 200 East 62nd Street", price: "$4,160,000"],
# => [id: "1181211", address: "#26A - 200 East 62nd Street", price: "$3,925,000"]]