Hello, here is my new machine

[A_Camera]

is this a good compromise?

http://www.ebay.co.uk/itm/CNC-0-8KW-...wAAOSw5cRZMk-X

You can't buy that one, as I said earlier.

1.) That one is a 65mm diameter and you have a 52mm diameter holder. Your Z is far too weak and small for that one, in my opinion it is not worth the effort of necessary modification.
2.) That spindle requires a VFD, and considering you asked above "what is a VFD?" I think the challenge of making it work will be too much for you. VFD = Variable Frequency Drive. Google for the details you want to know.

Just like I mentioned earlier, I think you should get a DC motor which is more powerful than the 200W which comes with your kit. I linked to a 500W, it is a motor with 52mm diameter and you can just simply replace your existing motor with this one. If the power supply is strong enough you can use the one you have, but if not then you may need to buy a stronger one.

The last option is to do nothing now, just learn how to use your machine, learn what you like and don't like in it and act accordingly. Maybe you are happy with it as it is, maybe you will want to buy or build a completely new one which is more rigid and more powerful. Don't underestimate plastic or fibre glass. Even those benefit from better machines or spindles.