Buying a used air conditioner scares me

Does buying a used air conditioner scare you? I know that buying a used air conditioner definitely scares me.

However, my wife doesn’t think that we can afford to purchase a brand new air conditioner.

If we were looking for a few window air conditioners, that would definitely be different. You could find a nice used window air conditioner for $100, and that would even be a lightly used window air conditioner. If you didn’t mind owning an older window air conditioner, then you could find one for much cheaper. However, when my wife and I bought this house, my wife made me promise that we wouldn’t use window air conditioners. She hated having air conditioners in the windows, and she told me that we needed to purchase a central air conditioner. I knew that having a central air conditioner would be expensive, but I didn’t want a window air conditioner either. I finally relented, but now that we have bought that house, we realized that we can’t afford a new central air conditioner right now. We probably won’t be able to afford the air conditioner until after the summer. I could purchase a used central air conditioner, but that makes me nervous. There is no warranty on a used central air conditioner, and there is no promise that the air conditioner would even last the summer. I don’t want to waste money, which is why I think that we should wait for the new air conditioner. However, that is a long time to wait for an air conditioner. What should I do?
Air vent