I did look and you can get the coated 20 lber's online through Walmart for 24.00. There are some very high dollar anchor's out there but if you do loose one of these it won't be a big money loss. The rubber coating is nice because you don't scratch up your boat. 20 lber's would be plenty for your 18 footer. You will have several different opinions kinda like asking about trolling motors or fish locators etc. These work well for me.