Have you ever been to a Phuket open market? If you haven't, do so, they are a lot of fun to visit & you can see a quantity of Thailands most famous foods. Yeah, you can go to the local grocery store & get everything you require, but nothing beats an open market experience.
Open markets are located all over Phuket on any given day; you must do your research. Once you get to the market it is very easy to get overwhelmed, but think of it as saving a bunch of money & getting some fresh food, you could literally saves hundreds of Baht by using the market. Very all Phuket restaurants pickup their fresh produce each day.
So my advice to you is, when you are in Phuket, find an open market & enjoy all the amazing foods from Thailand, it is a joy.