Vending Etiquette - To vend or not to vend?

I have only participated in one event and I didn't know if I priced my food right. I suspected my prices were too low because we were slammed all day. I never had a chance to leave my cook site and see what everyone else was charging because we had this long line all day! I don't want to make any enemies and I'm sure undercutting prices will do just that. We sold over $3000.00 worth of food and made just a few dollars over what we spent after their 80/20 cut. We did our price schedule something like this:
Single: 1 meat and 2 sides (your choice of meat) $6.00
Double: 2 meats and 2 sides $7.00
Triple: 3 meats and 2 sides $10.00
Grand Slam: all four meats and 2 sides $12.00
Sides were: cole slaw, potato salad, and baked beans
a meat serving was a pork sandwich, two pieces of dark meat chicken, two or three ribs (depending on size) and about 5 slices of brisket

What do you charge? What's fair? Is it really worth it?

Oh, ya... I spent twice that probably.
I do think I need to price each meat separately due to the difference in cost and then have single meat add on prices for people who want to try more stuff. Thanks for the input, would like to hear more...

We actually made a couple of hundred bucks, but we split that amongst the team, we did just better than break even. Lucky for us we sold out of everything. Also lucky for us, so did everyone else... otherwise we would have made some people mad taking away their business by underpricing. Just a little beginners ignorance on my part.

Around here where I am if I can do a sandwich and drink for $5 Ill do a mass amount. Families here are big and you can get that out of them but at $7 they will buy one and share it. I do burnt ends and shredded chicken only cause there is 2 other at my market that do pork and I don't want to compete. My plate is 1 meat 1 side and a can drink for $6.50. and I do 3 times the sales as $7