A fax modem board in a PC will receive and send faxes, however the only way to get a hard copy is to print the fax on the printer. And there is no way to input hard copy for faxing without the use of a scanner, which negates any savings from not buying a fax machine. However, if a scanner is needed anyway, then this method is a pretty good solution. Fax machines are available everywhere today at resonable prices. Brother is a very popular brand name that we have had good results from.
Plain paper is better but costs significantly more.
It is important to consider though, that a plain paper fax doubles pretty well for a copier. This is not true of thermal paper machines. Although they will make copies, the thermal paper is only useable in house. The printer fax combination has gained in popularity recently and there are several good ones available. Check out the links shown below for information from the Net on fax machines.