About 1500 square feet two bedroom apartment (EDIT: now that I think about it, it was smaller, probably 1100-1200 range, actually), electric heat with poorly insulated windows, the place on 70F for a month and ran about $700-800.

And that was over a decade ago, now could be even more.

Every next place I looked for had to have any other kind of heat but electric (don't care for AC - how we say in the old country: "it's better to sweat seven times than to freeze once").