I
HATE that. They release the minis in sets and there's only one or two in the set that I want. Wanted the Scabber but not the Slopper. Wanted the Chem Dealer but not the Beast Handler. Wanted the female Outcast Noble but not the Male (but only because I don't like that weird half-blob, half lizard thing on his shoulder). The only hope is if someone offers them separately on eBay, someone makes a not-dissimilar 3D printable version (as you said), or finding the appropriate bits to kitbash them... which can be a chore (and pricey) in and of itself.
As for Beastmaster minis, just find a appropriate-looking fantasy druid mini.

That's the nice thing about Wyrds/Psykers; other than Beastmasters (see previous statement), they don't have to have a particular look.