Milions of tourists pay 60 baht for dishes in Phuket. Millions of tourists stay in 400 to 800 baht hotel rooms.
Only a complete mug would pay 4000 baht for seafood.
August is rainy season on Phuket. With a car I'd probably skip Phuket and do lake and jungle experience at the national park in Khao Sok. Then head over to Khanom beach. Along the way Prachuap, Ban Krut and Bang Saphan.
Not so bad. I spent 10 hours in an airport. Ate 3 burgers spaced 2.5 hours apart for entertainment. Then the plane took off an hour late. All in all I took 3 flights plus waited 15 hours. Those burgers tasted nice.