I think it would depend on a few things:

- the location (neighborhood, type of building, outdoors?)
- are there other draws to the area (community events happening at the same time, heavy shopping traffic?)
- what kinds of crafts are you trying to promote (high-end stuff? small cheap things? boutiquey things? kids' stuff?)
- how well will it be advertised?

For example, I'd pay more for a table if it was in a high-traffic area in a neighborhood that has a lot of shoppers on foot who have disposable income, especially if there is some other community event going on that draws more people from other areas, and if the sellers have interesting, unique things to sell.

Some suggestions:
- avoid locations where there are already a lot of "crafty" people (grandmas, hip young-ish people in the mid- to low-income bracket) because they will just walk past all the tables without buying anything and then go home and make the stuff themselves!
- make sure you find a location where there are people already walking around with money in their pockets -- unplanned shopping is very important to nab when you can. Avoid big parks where everyone goes to play sports and leaves their money in their cars. Find locations where people like to shop casually and stroll.
- consider a few tables (and chairs!) with baked goods and coffee to encourage people to linger.

Great advice above.
Despite this being an artistic endeavour, it IS business!

- My first thought was that the price of the tables should be proportional to the expected sales and amount of marketing that will be done. Plus, are you going to provide tents? Entertainment? How will you create an irresistible BUZZ, or catch people's attention who are just strolling by?
- Usually the first year you would concentrate on getting quality crafters representing themselves, and build a reputation from there. How is your craft sale UNIQUE? [Modern is good start....]
- Competing with other events in the city makes things tough, so doing some homework about what else is going on is highly recommended. TIMING is everything. [Why May? How predicable is the weather then? ]
- Shaded windy spots in between city buildings makes for short browsing by customers ( eg the fair that was all summer in Yaletown on Hamilton St.) & blazing hot sun overhead makes for drained sellers - it's all about LOCATION, location, location!!