I have a muck boot like this from Sportsmans Warehouse in C Springs (nothing special, about $35). Gotta have it for a GC trip. I strongly suggest buying a pair in a store rather than online. Various boots in your correct shoe size can be easy/hard to put on.
I'm at GC at the end of April, too. I'm bringing the Chacos, a water shoe that fits me when I wear a thick wool sock, my muck boots, and something lightweight for camp. Pack your bedroom slippers!