ONE PUNCH MAN OVA | S1 "The Disciple Who Stinks at Storytelling" REACTION!

I would guess that Genos is rich, since he can afford all the upgrades that Dr. Kuseno does to him. Although it could also be Dr. Kuseno paying for this. I don't know. However, at the end of episode 5 of season 1, we saw Genos throw a big bundle of money on the table in front of Saitama to convince him to let Genos move in, so he should at least be pretty well off financially.