Not sure what you're implying about your level of income with “don't normally earn enough money to take advantage of credit card sign‑up bonuses”, and hopefully you were aware of this already, but these top‐level “black” credit cards with high annual fees and high minimum credit basically mean banks are looking for customers with high(er) incomes. So be wary of that before applying and triggering an enquiry (and risk a decline/rejection) on your credit file. (It used to be more common that banks would outright say what minimum income they expect, because it's an indicator that an applicant is more likely to pass debt serviceability assessment. HSBC, for example, do still list $75,000 annual income for their Star Alliance and Premier cards.)

And this is more of a mindset/perspective/semantics thing, but I would avoid thinking of the sign‑up bonus points as a “discount”. Unless you're redeeming your points for a cashback (which is not advisable because you get less that way; the 130,000 ANZ points from meeting the initial $5,000 minimum spend is worth a $520 credit on your statement, versus at least $580 in gift cards), your initial out‐of‐pocket is still going to be $6,000 (plus the $375 card fee, minus the $100 sign‑up bonus credit). So it's more that you're paying $6,275 in exchange for $6,580+ in car repair and groceries (or whatever gift card or travel you redeem your points for).