Most designers are willing to extend the "for personal use only" to sales of a few items at a craft fair... they just don't want their items mass produced without a license. Just ask if you are worried.
If you are making your own items from a photo, that photo is merely inspiration, not a pattern. No need to ask. In the fashion industry that is called a "knock off".
All that being said, I have yet to see any copyright lawyers patrolling local craft fairs.