You need to charge a lot more!!! I would paint the darker ones with a diluted white acrylic paint. Also maybe consider coating them with resin. You're s lucky to have found those! I live on west coast & our sand dollars are different. Lovely presentation!
As long as there’s no a double red flag flying you can if you want. They’ve been flying the yellow flag at Manasota & people have been in the water. I do not recommend putting your face in the water nor going in with open cuts no matter how small. We always use dial antibacterial bar soap when we get home from the beach. I think it’s personal choice & the red tide changes each day & sometimes even hourly. When we were there Saturday the water was fine for the first 30 min but literally 1/2 way through our walk dead fish appeared out of nowhere in the water and everyone got out as they fish were bumping into them. It was honestly super gross.