Selene Jean, Armor specialist @ Kuk system, was my first stop. After her work was done (and well done -- armor now lighter and better reinforced) I manually plotted a long-jump path to Deciat for the FSD work by F. Farseer. Taking a look @ Kuk system map, I found that all the mats needed for levels 1, 2 and 3 boost juice can be found there, including the Very Rare Polonium. The percentages didn't look especially promising, but the stuff was there, so I looked for it.
The area around the Engineer's site Prospector's Rest on Kuk B (3) yielded all the Vanadium I'd need in about 30 minutes. I also snagged my first Tellurium and soon had my fill of it. I spent a lot more time looting POIs than cracking rocks and still made quota.
Two Rocky Ice moons yielded plenty of Cadmium (Kuk B (7) A) and Germanium, Niobium and Polonium (Kuk B (8) A) for levels 2 and 3 Jumponium mix. The latter body was particularly rich in Metallic Meteorites that yielded lots of both Niobium and Polonium. I found at least 8 MM falls with 3-4 meteorites in each, and they gave up 4-6 lumps every time. Very rich. One was pure Niobium, 5 chunks, but by then I was full up of that element. Polonium was a little harder to come by but not much, I collected 21 units easily.
I now have mats for up to 11 Level 3 boosts (30+ LY for my mule), and many more of the levels 1 and 2 variety. Had I more time (and patience) I'm sure I could have doubled that, at the expense of other mats, of course.
More possibly useful data: On Kuk B (8) A (high MM incidence, three jump juice mats) my search field was in the general area of 25.95 x 85.18 -- lots of flattish terrain, fund to drive on, easy to see the 'rites against the ice and snow.
"First star on the right, and straight on 'til morning."