Corrupt a dark terminal — one you haven't switched on yet. Each reroll re-draws its machine tier as a gamble (it can go up or down), with a 50% chance it comes out Corrupted. Rarer machines earn more once you hardwire. Keep rerolling until you like it, then switch it on.
Your price rises only with how much you reroll — base for your first 10, then a little more each 10 (capped). One busy wallet never raises the price for anyone else.
Only terminals that are not switched on can be rerolled — hardwiring locks the tier. A reroll is two quick steps (commit, then reveal) so the outcome can't be gamed; the price rises the more you reroll (base for your first 10, then a little more each 10). Chassis, background and ticker never change — only the machine, its corruption, and its earning.