So you are looking for SEO help and are dead set on finding a firm that has worked in your specific industry, be it camping equipment, commercial pest control or hula skirts. Forget about it. The key is to find an SEO service provider that understands SEO rather than having a deep understanding of your industry. Some industry experience or familiarity is helpful, but anything lacking there can be picked up quickly. A true understanding of SEO and how it interconnects with marketing, PR, advertising, etc. is where scarcity lies.
So focus on finding a group that understands search engine optimization (SEO), rather than all of the nooks and crannies of your industry.