I found them in Palolim, South Goa, those shacks but that was almost a decade ago and Gotta has seen a phenomenal change in the interim so you may need to enquire a bit more but as per the latest information from friends who visited the place recently, it still remains one of the most tranquil beaches with shacks for accommodation. However, Gokarna is not very far from there and if you're looking for a long relaxed holiday than the good quality shacks at Gokarna and the serenity, compared to Goa, makes it a better experience but not so if you're looking for the typical Goa thrillomania..
1. La plage, Morjim 2. Shiva Valley, Anjuna 3. My fav the new Thalasa at Siolim ( haven’t been there after it has taken new avatar) but has to be best 4. Rudy’s (Suggested by many ) 5. Bobby’s shack at Candolim