I'm too far from the coast to be picking up beach glass, but you might try the Gulf Coast forum. It's up at the top of the page on every forum where it lists 'new to garden web', I think it's called--just looked but I've already forgotten! People have commented on having to cope with salt spray, and it covers all the way from Texas to Florida.

Beach Glass is readily available on many websites and auction sites like eBay etc. There are two distinct different kinds of Beach Glass: Real Beach Glass, usually sold by the piece and prices can vary, and Replica, or Faux Machine Tumbled Beach Glass that can be bought usually by the pound and is relatively inexpensive. Real Beach Glass is usually used for Jewelry and the Machine Tumbled Beach Glass is perfect for Crafts (like lamp or vase filling) and Suncatchers.

Here is a link that might be useful: Florida Shells and Gifts