I would suggest setting up an escrow account as well.  I know other government resellers have done this in the past when working with small government contractors such as yourself.  You would simply set up an escrow account and purchase the product (hardware) directly from the reseller under standard commercial terms with the relevant FAR flow downs (most resellers have their standard reseller agreement for transactions such as this with the basic flowdowns which should be sufficient to satisfy the terms of your prime contract) and have the product drop shipped directly to the government customer.  Once the government customer "accepts" the product (make sure final acceptance [and testing] is defined in any reseller agreement or Purchase Order Ts and Cs), payment is then made directly into the escrow account.  Since the reseller is paid first, there is very little risk to the reseller as long as what the government is funded and obligated to pay for the product, per its contract with you, is sufficient to cover the reseller's prices for the products and as long as the government "accepts" the  products.  Whatever amount remains in the escrow account after payment is rendered to the reseller, less any fees for setting up the escrow account, is your net payment.