Non Profit Seeking Donations For Party Supplies

I am working on a non-profit project and I have been delegated the task of seeking party suppliers that are interested in donating supplies, such as balloons, tulle, a heart arch, etc. For decorting our venue location. The event is a Silent Auction and is being held this Labor Day weekend. Does anyone have any suggestions on how to go about finding such suppliers. We would be happy to list the suppliers in our event programs and possibly provide links on our website in exchange for donations. The event location is in Central PA, but the exposure on our website is nationwide ... Actually worldwide!