Free for Thai people but 200bht for foreigners. I didn't go inside. There are plenty of real markets in Ayuthaya to choose from, Another one of those dual priced racist places where they feel its ok to extract money from white people because they think white people have more money.

The floating market was a bit far from the ancient city. It was large with a lot of fun activities and nice shops. However, the gatekeeper tried to charge us THB200 for each person by saying we must buy a pass to get in. In fact, that was a fee for riding on a 5-minutes boat trip around the market, and we found that there was no need to buy any such pass to get it!
Plus, we decided to have a lunch on the central island after checking the menu. Well, with the price at THB50 for a small dish of pad Thai, it was acceptable. However, when we ordered a bowl of THB20 lemon tea, we gave a note of THB50 but the waitress did not give us the change. We asked for the change, but they all just ignored us! Such a bad scam! Beware of them while visiting this place.

When we go into the entrance, they ask us buy ticket at 200baht for boat trip, we said we want some walking only, no need by boat; they said if not pay, cannot walk inside. Finally we buy tickets, the boat trip only 5 min. And then we find local people free to walk in/out, actually inside all small shops & canteen, it is good for tourist. But bad experience for the entrance.