probably empty cargo is the solution, other commodities may be found easier ..
Or any old nav beacon - found several wanted T7s flying around and picked up a few mechanical components.
Think I found some of these in planetary surface POIs. ISTR some Chemical doodads at least. Together with canisters full of expensive stuff (Gold was just about the cheapest) and lots of escape pods, which I left lying there. For one thing, my FAS has only very limited cargo space, and secondly, some NPCs now scan you while you're landed on a planetary surface, which could put you in a serious tactical disadvantage...
Same here, I know they're only NPCs but for people who play more dedicated explorers going into combat to get the best gear seems a little ... off.
So far I've found 1 (one) Chemical Manipulator since release, and I've been doing A LOT of hunting for them. The one i did get was on the surface at a wreck, along with a bunch of cargo iirc, probably guarded by skimmers. Seems to be 7 or 8 containers of cargo with one or two (if you're lucky) manufactured materials, or a bunch of escape pods with the odd container and maybe a material.
Have also tried going into RES/Nav beacons and killing wanted ships tends to drop 3-7 materials, but so far I've had no luck with the manipulators, especially as wanted trade ships are fairly rare compared to wanted combat ships.