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.
It is also possible to use the internet to send materials to a fax machine. There are a number of services which can be used, most of which cost money. This can be a wise investment, however, if you do not send faxes very often and do not wish to buy a fax machine or deal with services like FedEx.