Institute of Supply Management (ISM) explains the difference between procurement and purchasing:
Procurement is an organizational function that includes specifications development, value analysis, supplier market research, negotiation, buying activities, contract administration, inventory control, traffic, receiving and stores. Purchasing refers to the major function of an organization that is responsible for acquisition of required materials, services and equipment.
Refer to the Purchasing Guidebooks for more information about the purchasing bid solicitation process and drafting contracts.
Examples of RFPs, RFQs, ITB or contracts for various products and services are frequently posted on local government websites. Use Google to search for document samples:
Oracle ERP RFP site:.gov
HVAC "statement of work" site:.gov
Knowledge required for cost driver identification and optimal results in contract negotiations