Have used the Rustoleum galvanizing spray from Home Despot for a few years on our previous boat... a 34' sport cruiser with 18-20 knot cruise at 3450 rpm. So the props were turning at a good clip. The Rustoleum can was labeled "Professional"... less than $15 I believe. A number of boats in our marina use the same.
The boat sat at the dock during the week but was otherwise running in Barnegat Bay (salt water) almost every weekend from May into November. Applied it to the props, struts and shafts with good results, although like I said, we didn't sit at the dock much. At November haul out, just a power wash of the hull and running gear removed anything there. There were minimal if any barnacles or tube worms.
As of late fall we sold the sport cruiser and have a trawler that cruises at about 7k (single screw). Am planning to coat the prop with the same stuff after it comes back from tuning. Hopefully it'll keep the barnacles and tube worms off. Will try to report back in the fall. Spring is coming... honest.