How many supply systems does the Gov't use? There is GSA, but agencies have there own supply departments. From this Save web page, I found that NASA contacts with Lockheed for their supplies. One may think that by using the whole contracting power of the USA that the best deal could be made since the gov't would be buying in volume. Advantages are getting a better price due to a good bargining position due to the volume. Reduction in overhead due to consolidation of procurment operations. Reduction in buying costs and stocking due to only stocking the amount needed instead of 15-20 different warehouses in different systems.