I just got a 600 and 2000 credit on a heat pump I bought last year. Funny story, too, because most variable units don't technically qualify. The unit I picked did, but the HVAC people had it on back order and talked me out of it for a slightly older, slightly better variable unit. After a heated back and forth, I talked them into giving me an additional 2000 since (we thought) I wouldn't qualify for the tax credit and I was gonna wait. Fast forward to today, turns out I did qualify and I managed to bumble my way into a discount and a credit.

By the way, if you live in CA, you can see a distribution of what people paid because the Cali credit requires transparency. It's even got a list of the dealers, since they have to give that into when applying for the credit.

Last piece of advice, buy during an off season. HVAC is most in demand in the heat of summer, so doing it in the fall when it won't be useful gives you leverage. The baseline for the 2.5 ton unit was $16k (with non variable 2 tons at $10k) and I got them down to $12k before tax credits and rebates, and that included removing my old gas heater, capping the line, installing vents, revamping my attic, and installing a new sub panel.