Go and eat in the restaurants where all locals go, it's much cheaper and tastier! And it's safe, i haven't been sick once.

coconuts are NOT cheap here... whether its the skin colour of tourists or their accent, coconuts cost around 20-25 bucks... and in delhi, atleast a 1000 km away from the nearest seaside coconut grove, they come for a much more pleasant 10. even in beachside kovalam, you are unlikely to find pocket friendly coconuts.
however, do make it a point to try out the crispy jackfruit chips. these are pretty nice and decently priced.

If you like rice and if you like spice, boy have you come to the right place. Don't be afraid to try the local cuisine; it may not be the norm but it sure is tastey.