Steve, run down to your local NAPA store. They sell a TON of marine parts that are exactly the same as Mercuy parts, except they come in a plastic bag and not a box marked "Quicksilver."

Also, I dout your problem is voltage regulator, but a little thing called a "rectifier." When they go bad, your tac stops working, and your battery won't charge. Now rather this is the same thing as a "voltage regulator" or not, I don't know, but I used to pay about $15.00 for rectifiers at NAPA back in the old days. The one of Jefferson Davis Highway, across from DuPont was where I always got my parts. They might take a day or two or order them and get them in.