The real net prices at which goods are sold to those regularly engaged in the plumbing business are never or seldom stated in plumbing supply catalogues. Instead, certain prices are quoted which are much higher than the net prices, sometimes as much as one dollar being the list on materials that cost less than fifteen cents. To those regularly engaged in the plumbing business the various supply houses furnish discount sheets which show exactly how much may be deducted from the list price of every article shown or enumerated in the catalogues. These discount sheets, or quotations on certain things such as soil pipe and wrought pipe, are sent out from time to time by the supply houses to those on their mailing list, so that, by following them up closely, the contractor can keep posted at all times as to the cost of materials. There are two reasons for having a list price in catalogues and using a discount sheet to ascertain the real price. In the first place, if a catalogue of plumbing supplies falls into the hands of those who are not connected with the business they can form no accurate idea from the prices listed of the real value of the goods. In the second place, prices are constantly fluctuating, and if the net prices were stated in the various catalogues the moment the price of any article listed in the catalogue either increased or decreased in value, the list price would be valueless, and when many changes had taken place a new catalogue would have to be compiled. As conditions now exist, instead of altering the catalogue, at certain intervals a new discount sheet, which seldom exceeds eight pages, is made out and sent to the various plumbers on the mailing list of a supply house, and during the interim between the issuing of discount sheet letters telling of changes in price are regularly sent out to the trade.

An example of a discount sheet is shown in Fig. 35.