As long as any AI in the galactic community can mine some, you should be able to buy it off the market.
To be fair though, nanites are so incredibly rare. That sometimes the only node I have is over a nanite world that loses it once I teraform it so I can colonise it!
We should be able to make nanites from dark matter and living metal
Maybe like one nanite for 1 dark matter and 1 living metal