Thoughts on Sorotec alu-line machine

[JAZZCNC]

I have already bought the 180W JMC servos and power supplies. What is left of the budget is then 5150-6150€?

Cannot comment on the JMC servo's as I've never used them but power is power and 180W isn't massive so you'll have to be mindful of the weight and mass your moving around.
The budget is healthy though so definaltely possible to build a very nice machine.

The machine needs to be moveable later when I build my own garage. I am currently using my fathers. This is why I am opting for aluminum profiles instead of a welded frame.

Well if that's your main reason then it's the wrong way to think because while Aluminium is lighter than steel the total weight of machine this size will still be heavier than 1 or 2 men can handle safely so you'll still possibly need some lifting equipment. So why not just build the best machine you can and don't worry about the weight too much.

- Machine needs to be able to handle aluminum with good finish. The idea is that I could also potentially use it to build a VMC later that would be for milling aluminum and steel..

Again I wouldn't let this dictate the design of this machine because a VMC worth the effort requires building from steel and this machine won't machine steel to any great accuracy.

If it was me I'd look more along the lines of using this to make money and learn CNC then buy a used VMC that you can retrofit with new components. Or buy old Iron manual Mill and retrofit it to CNC. Both these options will be much better and far easier done than trying to build a VMC with a Router, no matter how well built it is.!

From where should I buy linear rails, bearings and ball screws? I have heard good things about BST automation.

Yes BST is a great place to buy from. Fred is the most helpful and trustworthy Guy I've ever dealt with and I highly recommend him.
Send him a message with your requirements asking for a quote including shipping and he'll get back to you quickly with a price. Mention Dean from Uk sent you and it may help with the price.