Hi there
I think anyone with a half ounce of brain would realise that Sacrificial Anodes at our scales of model would be very little use, if none at all. I think the gent who is asking the question really requires them for 'cosmetic value' to enhance the look/realism of his model. If not, and he does want 'real' ones I am going to look pretty thick

but I dint think they would work pretty affectively.
On the off chance that he is after cosmetic ones, they are fairly easy to make yourself. The way I have made small stuff like this in the past, is to make a small box up out of scrap wood and get meself some plasticine (not the playdough stuff)/similar modelling compound. Make your box up, as in photograph, roll the plasticine in then make yourself a one off of the item you wish to cast. Press this several times into the plasticine to make moulds - you could smear the moulds with Vaseline/petroleum gelly as its sometimes called, as a release agent - then with either the car body filler mix/or a casting resin - fill up the moulds. When they have hardened remove from moulds and hey presto one has items

clean off, paint to represent Anode, and stick to hull.
aye
john
Obviously, if you can find the address of the manufacturer and they are reasonably priced - i.e. to buy 50 would cost less than a tine of P38 car body filler/modelling material - you have to go that way!
why aye man
john