The cost isn't as good as solar though. a 1kw turbine is expensive.
I got an offer for a "essentially free" residential turbine including the pylon (8 to 10 meters, the legal limit for a "Kleinwindanlage") in SW Germany - just had to dismantle it and put it on my lawn. And of course pour a huge foundation [2x2m?] and have an accredited electrician do the necessary alterations. Nope. It didn't even produce enough electricity to offset the maintenance costs - no idea how I should offset the costs for moving it, even with the free capex.
And I did the math about 3 years ago: Prices for both PV and batteries dropped a lot since then. For late fall/early spring I would be better off by adding a PV carport (2 cars). I could also finally automate charging my batteries while electricity is cheap during Dec/Jan, might even be worth bumping my existing battery from 28 kWh to 42 kWh.
To be fair: The math might work out in the Northern Germany; but I would not bet on it.
Obviously, cost scales more than linearly with blade length but it’s a bit like big O - the n^2 factor dominates. This is why wind turbines have been getting bigger and bigger. And why the cost of domestic or small-scale wind turbines remains stubbornly high despite the dramatic fall in the average cost per MW seen for wind turbines - as the falls are largely driven by the ability to manufacture larger and larger turbine blades. While falls in costs for solar PV can be seen at every scale.