They range anywhere from $75-350 depending on brand, style, features, etc. A short sleeve/short leg spring suit is fine for now as water is warm. Full suits (long arms and legs) are more versatile. You don't need a super flexy, sealed neck, zipperless, ultra-whatever surf suit as you aren't paddling a board. Go to a surf shop and ask to see a range. Some of the lower cost surf models are more than adequate for tubing. Remember, waders are fine in enclosed areas like bays. Wetsuits are good though in that one may relieve his or herself (aka nature's warmer). With waders, you wouldn't want to do that and will have to get out of the water. Sorry to be direct, but everyone who surfs and dives does it.