Manufacturers will sometimes offer advertising support and even co-op money for dealers. This takes some extra work on your part to meet the criteria, but can absolutely be worth it! The products that your potential customer sells will impact the available co-op opportunities, but here are a few examples:

http://www.colemanhvacdealer.com/marketing-action-center.aspx

http://www.hvacdist.com/PDFs/GoodmanCoopGuidelines.pdf

http://www.weil-mclain.com/en/weil-mclain/resources/professional/library/co-op-guidelines/