In Spanish-language publications, the idea of "regatear" (try to get an artisan vendor to lower a price) is truly being discouraged and most thoughtful people, foreigners and Mexicans alike, agree that asking for a lower price on an artisan's goods is incorrect. Most artisans price their products substantially below a retail price. For example, if you shop at Mexico City's Museo de Arte Popular, the items are priced approximately three times the vendor's price if the vendor sold direct to you. At the Casa de ArtesanĂas in Morelia, the same is true. Worse yet, the museums accept the items on consignment from the artisans and a much of the time the artisan doesn't get paid at all for what the museum sells. The artisan has to go to the museum any number of times to ask for payment for an item or items that are no longer in the museum stores, only to be told, "Oh, that item broke," or "Sorry, but it's been lost somewhere," or "Come back next month, we don't have the funds to pay you right now."
If the vendor's stated price is more than you want to pay, say gracias and go elsewhere. If you hear a vendor offer an item to another client at a substantially lower price, an identical item to the one that interests you, ask if you can have it at the same price. You don't know the story behind the sale: maybe the potential buyer has purchased extensively from that artisan in the past and is giving a discounted price to a well-known client. For example, I know many, many artisans in various states of Mexico--as do many of you. If you or I have purchased items from Sr. Fulano in the past, he might well say, "The price is 500 pesos--but to you, it's 400." You don't know the reason, you just think you're getting the higher "gringo price".
If you look hesitant to buy, and the vendor OFFERS you a lower price, buy the item.
Watch for these words in publications about artisans' work: "DI NO A REGATEAR." "Say no to bargaining."