On-line trading services in which sellers post products to be auctioned and bidding is done via the Internet; providing a website whereby buyers of goods and services locate and receive quotations from multiple competitive sources and sellers of goods and services identify and bid on multiple new sales opportunities; document reproduction; computerized database management; on-line computer database featuring trade information in the field of construction management, project management, project estimating, project bidding, construction products, construction transaction tracking and management, creating purchase requisitions and purchase orders, monitoring the status of purchase orders and providing blueprint order tracking