“How did you prep it?”
Wipe it down with alcohol or another solvent.
“Did you prime it?”
You have to prime just about any metal to get the paint to stick well and for the colors to show up. With matte black, you could probably just use primer as the paint.
“Paint recommendations (I’m thinking powdercoated black)?”
Most autosupply stores have a good selection of spray paints. Matte black is a common color.
“Should I just pay someone else to do it?”
No way. Why pay a few hundred bucks and ship it off for weeks, when you can do it yourself for $20 and ride it the next day? I’ve painted 3 of my bikes in the garage.