Brian, if you're ok with a drill and hacksaw you could make them. There are plenty of big, heavy anodes for sale on ebay from which you could fashion yours. A step further, if you have a source of heat you can melt zinc in a ladle, nothing more than a big spoon with with handle. Make a rough mould in sand and pour in the metal. If you have a source of moulding sand, (Does IOM have a foundry?) even better. Do you need them every year? Make wooden patterns and have a foundry cast them for you. Just thoughts given the silly cost of the replacements.