Anyone with an AC window unit? Energy Cost?

[Bookak]

I have a Kenmore Elite 10,000 BTU window AC Energy Saver. I usually don't run it all the time in the summer because I'm worried about the power bill. I was talking to a colleague today and she told me that she has 3 window air conditioners working around the clock, and here the electricity bill is no more than $ 135 a month. It shocked me. I thought it would be in the $ 300-400 range. 3 ACs Windows work all the time. It did not get into everyday LIFE, air speed, and so on. I know that he is only 2-3 years old, and she also sometimes leaves the light on.

Should I turn on the air conditioner while I'm away? It sucks that I have to go home to an apartment that looks like a sauna. I also have to put olive oil in the refrigerator because it gets very hot in my apartment.

Thanks.