In my experience, I have about 1800 sq foot on first floor and 1600 sf in basement that shares an HVAC - I would not want this set up without zoning. the basement requires far less of "everything" than the first floor, so I can't imagine it being comfortable in both areas!

Dampers and controllers and thermostats that actually work are a cost - what is that cost relative to your entire HVAC? I'd figure it should be 15% or so more for a dual zone, I think. (based on total gut feel and nothing more!)

Yes that price sounds reasonable and like something you want and need. Alternatively you could use a package unit in the basement but that probably would cost about the same or slightly less.

We paid about 4k to zone our HVAC (ducts were already installed for zoned system but the dampers and dual thermostats were not included). So I think $3200 seems reasonable. However we only have 1st and 2nd floor zoned. Our basement is on the same zone as our main level. We typically close the registers in the summer and open them in the winter and it's comfortable.

The price seems reasonable. But just to throw out a few things.

Basements need very little space conditioning. But they do need some warmth when the house doesn't. It is very difficult to design a system to heat 1,000 sqft and not touch the 2200 upstairs. So today (ie Mid Oct), you might need heat in your basement but not upstairs. At $3200, you are getting system that can't do that. So you will get some heat pushed upstairs and someone will open a window to cool it off.

Similarly, in August, your basement will be cool while the upstairs needs a/c. Your system may keep all the a/c out of the basement. Great for temperature but bad for humidity.

Why you would want to work full time in a basement, I don't understand. Forced to by circumstances? Sure, but as a preference, you might want to rethink that.

For full time activity, you want an independent system down there with a separate dehumidifier. That could be only incrementally more.

Zoning is tough to get right.

What your default plan appears to be is a single system throwing air to 3200 sqft. What $3200 buys you are dampers and controls. The airflow may slow down or may not for $3200. So what you might be asking is to jam 3200 sqft worth of air into 2200 sqft or 1000 sqft - which is generally not acceptable. So the dampers just modify the airflow a bit. Can be truly bad - and often is. Poor equipment life, excessive airflow noise etc. 2 zones of equal size is a lot easier and still mostly done incorrectly.

It's not clear what you would be getting as a zoning system and it's equally unclear what the base case system is. The spec you provided "95% Gas Furnace - 1 Zone, 13 SEER Heat Pump AC", might imply a dual-fuel system (utilizing a heat pump with a gas furnace back up) or it might have misstated that air conditioning is provided via a heat pump versus an air conditioner. We don't know if the burner is multi-stage or if the air handler is variable speed. Those features would be important when considering the feasibility of any zoning strategy

Zoning systems are far more complex than just installing zone dampers and a second thermostat! Most HVAC companies have no idea at all how to install them correctly and it becomes an ongoing and longstanding headache. I would recommend a single system for the main house and a second, smaller system (probably a heatpump split system or minisplit) for the basement area. This will cost a little more but will be much easier to install, maintain, repair and operate.

I agree with sktn77a's advice. Given the very different heating/cooling load in a basement versus above-grade living spaces, a separate, appropriately-sized system will operate better and reward you with enhanced comfort.