Some options:
-You can match or come close to the price of similar produce from a local health food store.
-You can find a similar scale/quality vendor at the market and talk with them about pricing.
-You can wing it, and start high and lower it if necessary.
-You can make a short list and ask folks here what they sell those items for. (but get ready for a mix of answers)

In time you'll get the idea of pricing. For now, try to match others and don't undersell fellow growers that you would likely prefer as allies, not enemies.

-Mark

Match the prices of the vendor most like you. If you don't sell by weight and they do, ask if they would weigh your basket. Explain that you admire their product and don't want to charge too little. Several vendor friends of mine are willing to help a new vendor as long as they know that the 'new guy' isn't out to undercut them.

I found this extremely challenging my first year and I still brew on price when adding new things. I work in pricing at a grocery store and go write down prices for all produce I sell to compare. Looking at the other vendors' prices is crucial but sometimes you want your price signs printed ahead of time. I asked around online my first year and that helped but it is very specific to each market. Plus no one can say how big a bunch is. When I think my price is too low I usually make the bunch smaller rather than raise the price. My boss always says you can go down but not up. Start high and drop when necessary!
Produce is one thing, then there are plants, canned goods and baked goods too I always have to make decisions on!

I think it is best to have a one week sale when you have too much of a crop rather than lower the price. That works very well. Too many peppers? I do 2/$5 quart basket rather than $3 and people buy it. Certain crops like potatoes are something I can't sell at the same price as the bigger vendors so I generally don't sell them, sell only specialty taters, or put in different sized containers than them.

Anytime you can do even dollar pricing it is better, but 50c increments are ok once in a while IMO. Also good to clearly mark everything right next to it- not a big sign like at a fast food restaurant.

All my prices were quarter increments, and after doing the same market for more than 10 years, pricing was the hardest thing to pin down.

I like to use either cheap index cards (easy to change) or laminate cards with everything except price then dry=erase the price in. Easy to change. (If the laminate cards get foggy, then just clean with glass cleaner and ready to go again). Plus BLACK dry=erase works best, easier to wipe off and don't stain as easily.

I try to be a better deal than Wal-Mart. My market is in a fairly poor area of the country, so that's likely not relevant for everyone. But I want shopping at the market to be a money-saving experience, not a luxury that only some people can afford.

I am not going to try to compete with Wal-Mart, but I hear what you are saying, Cole_Robbie.

We have some pretty affluent areas and I refuse to chase those customers...butter them up with all the fashionable and political farm speak....and sell high. This is true even when I have very nice produce. I have never had a lot of money and I know what it is like to be pushed aside for that. I work on a somewhat clandestine sliding scale with a fair price at the top. Something like what I would pay if I wanted the stuff.

I don't compete with WM either, I always am HIGHER and push the FRESHNESS instead of price.

My DIL came from a city and refused to eat apples from the store, just didn't like them. Grandkids are the same now. I had to introduce her to fresh ripe apples, after tasting them, she's hooked. The grandkids will not eat the apples in the school lunch, and after visiting/eating with them one day last week, we understand. Those apples that the school gives to them for 'good nutrition' are as green as most of the stores. No taste.

Thanks for the comments. I think I'll shoot to price a little higher than WM, but not too much. If it looks like I'm underpricing other vendors, I'll adjust. I like the idea of adjusting size rather than price in that case.