Aphawa Floating Market
Amphawa floating market is about 65km south west of Bangkok, technically in Samut Songkhram really. The market itself operates every night. Plenty of delicious food is available, including fried squid eggs (Kai Pla Muk Tod), oysters, mussels (Hoi Tod), squid and lots more. Some is cooked on boats floating in the middle of the market itself, while other food is available in the shops and stalls surrounding the river. There are numerous homestays available, which can easily be spotted walking through the market. I don't know about general costs yet, but will check it out in the future. Lots seem to have great places for chilling out above the river and enjoying some snacks. This is also close to the morning floating market, I'm told, so may make a good launching point to get there early.