Is located in Hua Thanon, funnily enough, which is not too far from Lamai. Coming from Lamai direction Nathon, you pass Sabeinglae restaurant and keep going straight. After a couple of kilometers, there's a 90 degree right curve, if you go straight in that curve, that's where the market is located in Hua Thanon. It's one of the villages on Samui where there still are a lot original Chinese style buildings.
The market is a fairly straightforward relatively small affair. On your right hand side, coming from the 90 degree curve which I just described, you'll find a fresh food market at your right hand.
The market itself is on this narrow street, first building directly on your left hand. Around the market are a couple of small shops selling all kinds of bits and pieces.