At the very end of the sponge docks, there are a couple of fishing boats that do bring in a daily catch. There's also a good fish market there with a variety of locally caught fresh fish, some of which (such as the shrimp) appeared to me brought in from the open fish market. Tarpon, gouper, and rock fishes are good buys here.
In the 1920's there was a sponge exchange for the fisherman, but now that is all gone, and most of the sponges sold in Tarpon Springs are imported. Nevertheless, the selection of sponges available at the sponge docks really is pretty amazing. At the first souvenir shop, I began stocking up for gifts, but then my friend recommended that we go shop for sponges from the street vendors along the docks. So, we found a sponges only vendor who had some really large sponges at reasonable prices. These are outdoor vendors with no over head, except their city vendor permit, and they will fold up their business and disappear at dusk.
What to buy: There are several species of sponges. Some are really soft and others slightly less so. Buy the smaller soft sponges for make-up and facial cleaning, and larger slightly more abrasive sponges for back scrubbers. There are also large bowl shaped sponges that are great for planting orchids or bromeliads.
What to pay: Prices are negotiable. Prices generally vary by size and shape, with the largest ones being $10-$15. I bought several nicely shaped ones, and then got tiny make-up sponges for free in the bargain.