Know-How Exchange : Advertising/PR

We are a fast growing property preservation company completing services to Regional, National and Government agencies. We do increasing occasional referral work for banks, large Realtor companies and individual Realtors. Obviously the money is better working directly for banks and realtors, but we have not found an advertising solution to target these folks and organizations directly. Since we would prefer not to spam folks or do direct walk ups (as these types of professionals hate) I feel there must be a better, cleaner way to touch these folks in a non offensive way. We have searched in vein to find one. We do a lot of local rag "service" advertising, flyer and business card mailers without much success. (I don't think this venue is much frequented by the target audience or if the mailers ever reach the right folks) Any suggestions or tips would be greatly appreciated. :)