Information: It's not about 1 shop but in all the markets and shops along the main street you can find just about anything you want from cloths to shoes to souveniers to electronics etc.
Once off the boat in Thong-Sala you will probably see ice cream sellers on moterbikes  and other food merchants and then as you leave the jetty you will pass under a big welcome sign that leads into Thong Sala's main street and shopping area.