Sometimes the temperature does not decrease with height in the troposphere, but increases. Such a situation is known as a temperature inversion. Temperature inversions limit or prevent the vertical mixing of air.
Middle range machines can cost on average $400 and are often multi-function with copier and laser printer capabilities. Finally, high-end machines which offer high speeds, high capacity and high resolution come at a higher price-expect to pay $1000 - $2500 for such a fax machine.
For about $10 per month, you can send and receive an unlimited number of faxes, using your computer as the fax machine.. If you don't yet own a scanner, I recommend investing a multifunction printer (one that can copy, print, and scan) that has an auto document feeder (ADF).