My answer to Does GSA Advantage overcharge compared to the free market?
Answer by Ken Larson:
GSA Schedules are intended to be competitive.
One can find the same item on many company schedules and rates will vary so buyer should shop the domain or put out a Request for Proposal (RFP) on FEDBIZOPPS or the state procurement site and include GSA schedules as a bid vehicle.
GSA negotiates thousands of schedules and makes them available to government agencies at the federal and state level.