I made the mistake of going to market 28 before I visited Chichen Itza. One thing you have to understand is that as you are coming into the area, check out how these people live. Most of the masks are hand made on site and are made by Mayan descendants. I did not feel accosted or even intimidated at all, because a simple shake of the head and they said nothing else.
I would love to visit again and go to a different site. Not because of the vendors but simply to see something new. If you think these people bother you, take a trip to Market 28 for 10 minutes and you will understand what pressure really is. (Yucatan Today Editor's Note: Mercado 28 is in Cancun.)