I I found a “Basic Commendations Schematic” vendor, but all of his selections were greyed out, that is, not lit up, and they all were “schematics” (whatever that is) requiring Level 53.
Schematics are needed to craft things with crew skills.
To purchase items sold by that vendor you need Basic Commendations, which are a different currency than Planetary. You start earning them around level 50.
There was also another area for commendations, but these were for specific planets, not just “Planetary Commendations”.
There used to be a different type of Commendations for each planet, but thankfully they did away with that. Now you can use the same currency, Planetary Commendations, to buy from all those planet-named vendors. The planet gives you an idea of the item level, although sometimes you have to check the next planet's vendor to get the best gear for your level. It's a good thing that they're all close by on Fleet.
Keep in mind that some full moddable gear pieces cost 10 commendations, and some of them cost 14; whereas a full mod upgrade for a moddable piece costs 11 commendations (7 armoring, 2 mod, 2 enhancement). Most of the time is cheaper to upgrade than to buy a full new piece, but not always.