I'm looking at building a router using parts mostly of AliExpress, I've listed them below. They all come in 'kits', ie the steppers come with everything needed to run them. It seems cost effective this way - are these chinese kits up to the task?
Hoping to be able to work woods and plastic, with the goal of soft aluminium down the line. Would be very happy with 4 thou accuracy

Spindle + VFD:

1.5kW Square Body, Chinese, Ali Express ER11 Collet With VFD

https://tinyurl.com/y8vdwslj $260 USD shipped

Steppers:

3 Axis Kit Nema 23 With power Supply With drivers With USB board

https://tinyurl.com/y9yfq5vy $152 USD Shipped

Linear Motion

Lengths are ball park for now. Seems cost effective to go longer, but then the structure would be less rigid. need to think here.

Linear rail, block and ballscrew kits 4x 1200mm rails with 8 blocks (x,y) 2x 300mm rails with 4 blocks (z)

https://tinyurl.com/y7p6ctgp $418 USD shipped

Total: 828 USD

Questions

As a starting point how does this look? Anywhere I could cut cost? anywhere I should spend more?
For the Stepper Motors, am I correct in thinking that with the supplied USB board I should be able to control the steppers from mach3 USB?
I've heard about smooth steppers - are these an alternative to the USB board? what is the point of them?
Thanks for reading, any replies are massively appreciated!