BST automation on aliexpress / Fred/ is not an unknown supplier. I bought from him before a month all ball screws and Hiwin rails and carriages. Everything was machined to 0.01 tolerances and fit perfectly. All rails,carriages,ball screws, nuts and supports cost me what here would cost me only the carriages. Split your purchace when paying and avoid customs stating the half amount only. No problem from their side.

Dont start your build until you have all the before mentioned including spindle mount, as many times they will send you whatever they have at hand, meaning the ball screw housing and spindle mount different from the pictures.
Yesterday had to redraw my build entirely, due to this. A small price to pay.

Spindle is not same as router. I would like to see somebody cutting soft plastic and aluminum with router, the way that can be cut with spindle. No doubt for me there. There are other benefits like trip when problem, speed control directly from CAD/CAM and so on, worth the money. 2 mistakes on a expensive material that could be avoided by the spindle PC communication will pay you the spindle.