Problem with life vests is that each brand seems to be sized differently. You might get a "Large" from one brand that is the same size as an "Extra Large" from another. So its definitely better if you can try them on.
That said if you are in the states, Dick's Sporting goods just had a good sale on many different brands of vests. They had some very nice O'brien neoprene vests (50-75% off). I picked up a couple, and have been very happy with the quality and fit. I don't know if the sale is still on or available online. Other places that have decent prices are Gander Mountain and Bass Pro Shops and they both sell online. Watercraft Superstore carries Jet Pilot vests, at good prices, which are a very nice vest for riding a pwc: Jet Ski Parts - Watercraft Parts - PWC Parts - Watercraft Superstore
Thanks for all that information, it is greatly appreciated. I am going to Dicks Sporting Goods tonight to see what they have. That watercraft superstore has a lot of stuff, thanks for posting that link!