Well in the end I went with an ATC spindle because why not. I chose the JGL-80/2.2R30-20 high speed one.

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Now the spindle comes without a VFD since Jian-Ken supposedly can't provide these.
Any idea which one I should choose?

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Looking at the specs there is a lot of VFDs to choose from.
Probably the most budget friendly is the AliExpressSpecialButBoughtInEurope "RS PRO" one.
Or maybe I should go with a Siemens one?
Originally I wanted to go with the same Mitsubishi VFD I have now (but a lower rated 1-Phase model) but that one is only 400Hz max and this spindle is rated up to 500Hz. I have no idea how many rpm would I loose but hell I paid for 30k I'm gonna use 30k.

It would be really nice if the VFD would be around the £400/400€/$400 mark or less.

If there aren't any VFDs I can source locally could you please recommend an AliExpress/Alibaba one?