Hello harsh ,I will be happy to solve your travel query as best as possible from my experiences .
*Gokarna is famous for its beaches and one of the shiv temples with large statue , beaches here are so much scenic , surrounded with mountains,offer a perfect place to relax and enjoy .
*pondi is famous for beaches,water rides , diving ,streets ,food and many things and days are less to explore this place fully .
*kunnur is famous for green treks and perfect valleys.for best experience try to travel here by winters .
*but as you mensioned your budget ,it's preferable to travel to Gokarna as there's less crowd,great scenes and amazing places to relax .
*being a enthusiastic traveller, I have a small suggestion for you.I checked online and found that the best deals are available at tripoto itself .
here are the links. https://www.tripoto.com/Gokarna/tour-packages
HAPPY TRAVELLING 😊☺️☺️