According to some folks around here, you can "eventually" get everything via mission rewards, but the big question comes down to HOW LONG is that going to actually take?

And... Is that claim 100% accurate?
I pretty much bailed on Engineers after the first visit to Farseer and my first FSD "Downgrade". Notice I said "Downgrade"? Thats because it was! Despite all the work and time I spent collecting all the gold coins.... Errr..ahh... I mean "Materials", I ended up with a BAD ROLL and my so called FSD upgrade ended up lowering my Python's range instead of extending it.
That was all I needed to see thank you very much! I basically shut the book on Ye Old Engineers that very day and haven't bothered with it since. Before I left the Farseer Complex however, I did save the Blueprint for the next FSD Wild Goose Chase aka GRADE 2.
Despite the fact that I have expended ZERO effort or focus into gathering all the required Magic Tokens.... Errr... Ahh.... I mean "Materials", I have at least half a dozen of the three "Micro Resources" listed on the Blueprint. But the "Commodity" required (1 unit of PRASEODYMIUM) has not as of yet shown itself in the course of my daily ED gaming sessions which are comprised primarily of doing missions off the mission board.
The description of PRASEODYMIUM says that it MUST be "MINED", so apparently there are a few exceptions to the often bragged... "I got all the materials I needed by doing missions" solution.
I can't tell you the precise number of missions I have done since I stopped bothering with Engineers back on May 27th, but it has got to be over 100 at least. Might even be as high as 250 individual missions completed.
So... Take all this how you will. More than likely at some point you are going to need to do some Asteroid mining with your ship.
