Many of these folks purchase their stock at garage sales and auctions. Because of the nature of their stock moving the merchandise is the key to success. Buy low, sell as high as possible is their credo. This leaves much room for negotiation. If you are at a weekly, monthly, or perhaps yearly flea market the key is to move quickly, negotiate firmly and don't be afraid to walk away if you are in doubt.
Some flea markets are at permanent sites with booths similar to the antique malls.
Many antique dealers sell their low end merchandise at flea markets. Look for the lone cup, plate or incomplete set here. You will have ample opportunity here to practice identifying chips, cracks, stains and other undesirable qualities for most collectibles. The level of service here is usually much lower than in the stores mentioned earlier. A trained eye is a must, so maybe bring along that expert that has been wanting to go with you every since you started collecting.