I just wasted 2 damn hours hunting this shit down from merchant to merchant. I probably visited all 5 planets & 3 moons of my damn star system TWICE but no luck. I was going crazy man lollll. I ended up waiting for a good 5-10 minutes at the space station and talking to every damn ship that came in until one of them finally had some damn antimatter to sell.
Now, I'm ready for my first jump. However, this galaxy ain't ready for me. I will unleash such fury upon anything and everything in my path that the gods themselves shall contemplate their own existence.
Do a scan as soon as you enter your new system, and there's a good chance you'll get a waypoint to the antimatter recipe