We know that you love creating technology plans and writing RFPs, and we know that sometimes, you probably wonder if you really need to write up an RFP. Here are some guidelines to help you decide if an RFP is really what you need:
"An RFP is usually drafted at the end of the requirements-gathering phase of a project. RFPs are typically most valuable in large, complex, or high-impact projects. Small projects with budgets under $10,000 usually do not need to go through a formal RFP process unless the projected impact is anticipated to be substantial. If you have a much smaller or simpler project, you may wish to consider an informal process instead of a formal RFP process."
From Npower via TechSoup - read the linked article for more details and help on RFP writing.