That really depends on what you do and how you stay in Goa, and the season.
During the off peak season, you can get cheap rooms/shacks from 500 per person per night. (Specially if you're in a large (Read More)group). Renting a self driven car is about 1200 per day (from what I remember), and 300-500 for a good meal.
Of course, if you're going on a luxury trip then you have a huge array of luxury options to choose from - there are a lot of fancy 5-star hotels in Goa.