Been to thailand many times but not Koh Samui and never had any problems,buffet breakfast in 4 star hotel about 2 euro, dinner in good restaurant 3 courses about 15 euro for two including drinks, wine is not big in thailand, beer about 2 euro per pint bottle, get two glasses.
Eat from a barrow on the street if there is a queue, main course ie. pad thai noodles, sweet and sour Moo(pork) gai(chicken) about 60 cents,
Shopping depends, but generally quarter the Irish price .You will be accosted by Indian men to enter their shop and have clothes made to measure, if you get a good one the value is terrific, be careful who you ask for recomendation as everyone is on commission. last month I had 2 shirts and one pants made, I picked the materials paid deposit and came back the day after, all was good, total cost after much bargaining beforehand 38 euro.
check out [broken link removed] [broken link removed] general info.
[broken link removed].com for hotels
enjoy,