Although many boats of that dimension often have problems that need smart tabs, or trim tabs, I have never seen anybody spend the money to install them on such a small boat. However, they do look shot, like esquired said.
I have seen cast aluminum transom braces, and bow braces new in certain places. Couldn't tell you where though. Also, unless you can get some genuine Starcraft ones, aftermarket ones aren't going to match what you have, so you will need to get a pair and install them together so they match. If you can't find any (check ebay as well) a metal shop could easily form those out of 3/16 aluminum plate. Fairly simple design (formed transom gusset that is) provided there is access to large capacity press brakes.