My favorite show hands down is the Salt Lake City Downtown Farmers/Craft and Art Market in Utah.
I did that show for 7 yrs and would do it still if I had not moved out of State. It was only 20 dollars a week and they had roughly 5000 + visitors each week. It was on Saturdays from 8am to 1 pm and my sales were consistent and very good each week.
The Downtown Alliance were wonderful to work with. Very accomidating and always quick to answer questions or help you out if you needed assistance. This show actually spoiled me to other shows. It was so much fun and is still a big event each week. I really miss doing that show.
I have a hard time now doing shows that are 3 days long ,10 hrs a day and really miss the market. If your city has a farmers market and they allow arts and crafts I highly reccomend giving it a go. You cannot judge the success with one week though. You may have a great Saturday one week and the next week is a dud. The up side is they usually have very low vendor fees (Under 20 dollars) and you are not there for more than 6 - 8 hrs and only 1 day.
The new city I am in only charges 2 dollars for a table. They are just starting out and have a small crowd each week but it is growing and you can't beat 2 bucks.
It is a great, inexpensive way to test the market and see if your stuff sells before doing a more expensive longer show. Check with your local Chamber of Commerce and they will let you know what is in your area.
Remember...You don't know if you don't try.