I am still making Mk-9s, and making a pretty tidy profit off of them.
The secret is to use biochem, cybertech, and artifice toons to make the mk-9 components then mail them to an armormech, synth, or armstech toon to make the kits themselves. If you go with the latter 3 the cost does rise considerably.
Plus if you have those latter three toons cranking out augments (blue and purple) when they aren't making MK-9 kits, you are golden.