Last year my 20 year old heat pump/air conditioner bit the dust in the middle of summer in Richmond VA. Temperatures were high 90's and a RH of %100. We immediately got a quote to replace it and were shocked it would cost $6,000!!!!
After looking online I realized I could replace it myself for $2,000. It would take 8 days to get to us. My wife and I made the decision to endure a week of heat to earn a easy $4,000 and this would make us more mustachian!!
Well we barely survived that week, we were both irritable and did not get very much sleep. I ended installing the unit the same day we got it but had to wait a extra day to get some one to vacuum the line set and braze it all together.
So a year later it's still working great, however we just sold our house and had some issues. It turns out when we had no air conditioning for that week all of our interior wood trim absorbed moisture and expanded and breaking all calked/painted joints. Our home inspection flagged this and we were forced to have the issued examined by a expert. We also had to remove all the old calk and put new calk in and repaint the trim. The inspector estimated it at $2000, I fixed it for less then $200 however I sunk almost 20 hours of labor into it.
The point of this story is be cautious of what people recommend to save money. In our case we still came out ahead. However what if we read a mustachian article and felt like using the AC was a financial sin and for no other reason stopped using it? The couple hundred dollars we would saved would of been negated.