High accuracy, large build area, for 500 bucks range. Exist?

[curious aardvark]

No idea if it'll print at 0.05mm or not. To be honest, that's Not what you look for in a printer.
you'll most likely NEVER print anything lower than 0.1mm and even then you'll most likely use 0.2 and 0.3.

Unless you want to wait 3 weeks for a small print.

For parts for airsoft guns, 0.2 will most likely be your default resolution.

For what it's worth the spec does state 0.05mm

You might use it once :-)
And then decide that life is too short.
Prit the same part at 0.05, 0.1 and 0.2 - odds are there'll be so little difference you'll stick to 0.2 for most things that need precision and 0.3 for everything else.

It also claims 100mm/s print speed.
What you'll most likely be printing at is somewhere between 20-60 mm/s depending on material and model.