Being a regular customer has gotten me more results, also ASKING is important. You never know what can happen until you ask. Dont bother with trying to make it seem like "your bartering" because there really inst anything in it for the other side. They are doing you a favor, many people, including small biz owners, LIKE TO HELP. and enjoy the idea of being involved.
My current project has both of these aspects in one location.
Iv had it in the back of my head for some time that the owner of the local bodyshop in my small town had some amazing cool cars that would be great in a film. So the first "opportunity" I had to patronize HIS business, I did so! Nothing big, somebody knocked off my mirror... anyway.. by no means through this interaction did we become more then acquaintances, but I made a point to wave, say hi, etc.
A few months back, the idea of "The Hot Rod" came along. I went it to the shop, said hi and asked straight up to use one of his awesome cars in the my short movie! Well, we started talking, he got excited, we hoped in his commuter car, drove up to his house, started up the Charger RT 440, pulled it out, drove it around, laid some rubber, took some photos... next thing hes showing me ANOTHER car, asking me to take my pick for the JUNKER (a heap that needs to be in the ending of the story) that I also need, and hes VOLUNTEERING to tow it out to the shoot...
The moral to this story... YOU ARE ALWAYS NETWORKING, and don't be afraid to ASK.