TTach military markets basically always look like this.
One high-tech capital, a couple high-tech frigates, and everything else is mid-tech with a smattering of low-tech. I've found exactly 1 Medusa on a TTach military market, and 5 Medusas on the black markets of the same planets. Given that you can get mid or low tech ships everywhere that's not a TTach market, and there are very few TTach markets, I think they should be almost entirely high-tech ships. Otherwise high-tech ships are just way too hard to find.