I need a windoz PC -

[Beardy]

I need a computer to run a windows 10 or later only software app and we’re an OSx household.

What’s the most cost effective way to achieve this in these here modern times?

[Kim]

Obtain a non-technical-person's old laptop that has recently been replaced due to general cruft and sluggishness (rather than, say, exploding power supply or eaten by a dog), and perform a clean OS install on it.

Or virtualisation, I suppose.

[StuAff]

If you have an Intel processor Mac, even a fairly old one, Win 10 should run natively on it. If you've switched over to Apple Silicon (M1/M2 chips) then virtualization is apparently very effective.

[Mr Larrington]

Wot Kim said.  Second-hand Win 10 capable laptops can be had for not much money – my Dell was about £200.  I just wish it had one more USB port chiz.

[philip]

Trying virtualization, or dual boot, can be done without spending money; that might be the most cost effective depending on how you cost your time.

Dual boot uses Apple software: https://support.apple.com/en-gb/guide/bootcamp-assistant/welcome/mac
Virtualization uses vm software which can be free: https://www.virtualbox.org or cost you money: https://www.parallels.com

Either way you also need Windows 10/11 but Microsoft allow you to download and install without a licence key these days, only a few things are disabled.

Virtualization is probably the most convenient way to run a single app, provided you can get it set up and installed and the vm can access any hardware required by the app.