Can anyone tell me what would be the best way to get from Pattaya to Bang San Beach if renting a car or bike is out of the question?

Bangsan beach is near Chon Buri. If you don't want to rent a bike or car, get a bus to Chon buri and take a local taxi from there. Even if you get a metered taxi in Pattaya to take you there it wont be too costly.

At the North-East side of the T-junctions: Thepprasit Road - Sukhumvit, South Pattaya Road - Sukhumvit, Central Pattaya Road - Sukhumvit and of course at the Pattaya North Bus Station, buses depart for Chonburi, passing Bang Saen.

Get off the buss just pass Mongkon Market and take a Song Taew to the beach.

Thanks guys.