Goa has many dive schools where they offer different course. So if you already have diving experience and want to go for PADi course or certificate course it is above 8/9k and if you want to go for fun dives (for 20/40 min) they cost 2/3k ! You can choose these two dive shops which are reasonably good and gives good experience. 1. Dive goa at Candolim and 2. Barracuda diving at Baga. However scuba at Goa isn’t that great experience as we have destroyed marine life there.
It normally costs around 2k along with transports food, and it depends on the season. everything in goa depends on the season and if you go in season the prices can get double and if it's off season you cab work it out for cheaper rates