I would just go into some of your local pet/feed stores and ask for samples.
I didn't realise they had dog food samples and when looking for a new food for my yorkie, the pet stores would give them to me to try. I would try a few different stores as they all carry different brands. The last pet store loaded me up with a large variety of samples. If Bailey doesn't like it, I throw it outside to feed the squirels and birds. They love it!