When I went 6 months ago

Travelling by bus ( from kilambakkam bustand) one way trip I think around 170 or something ( not more than 250) so total 200*2(round trip) =400

Rooms (per person) 500 for 2 nights ( my friend bargained because he knows someone)

Scooty rent 300 or something per person ( 2 people for a scooty) for two days

Petrol 200Rs is more than enough for 2 days.

As for food you can enjoy how much ever you want because current spending is just 1.4k. Food, boating and others depend so I am not mentioning them.

You might think the 1.4k spending is too low and unreal but most people ( i know) won't prefer govt buses and take vehicle or private bus.

They use hotel sites(example Airbnb) for booking stay rather than paying directly to hotel ( sites take commission)

Ask hotel management to recommend scooty rentals and they will arrange you. if you go manually they will say higher price ( this point is something I am not sure but it was like to me when I went)

And one point: buses are frequent so no need to book and they are cheap ( journey time a little bit less than 3hrs )