There's no way to overcome this problem at a theoretical level without people up the supply chain accepting Bitcoin.
People up the supply chain will accept Bitcoins if it is in their business interests to do so - so the question becomes "under what circumstances is it going to be in a supplier's interest to accept Bitcoins?"

For a startup, the initial barrier to trading (especially internationally) in Bitcoins might be lower than other forms of payment.  The costs may be lower so they can sell goods for a lower price than their competitors while making the same profit.  If you are the only supplier accepting Bitcoins then that might bring you some extra sales too.