I suggest that the government, at either an agency level, or even a government wide level create an in-house "CraigsList" type of system. The initial system would be used to identify existing supplies that are no longer needed by the office that has the item(s), and offering such supplies to other government offices that are in need of that specific item. A good example would be that in my office, we just put in an order for toner cartridges for one of our fax machines to cover the next several months. We now have 4 new toner cartridges, and our fax machine has just failed and is being replaced by different model fax machine. We now have expensive items that we have no use for. There are likely other offices in need of these same cartridges and additional government money will be spent to obtain them. With the system I am proposing, before a new purchase is made, an office could check for availability and obtain items already paid for. This same system could be used to post a list of needed items as well, so if funds are not available, but the need still exists, an office that has the item and can do without it and the office needing the item will be able to interact with each other and resolve the immediate need even in a period when there is no available budget to obtain it otherwise.
This type of system could potentially be applied to equipment as well, however, I am aware that there may be some administrative hurdles to address when such assets are transferred (but logically, since both the donor and recipient are truely the same (the US Government), there really hasn't been a disposal of the asset).