Hello and welcome.

If you have the time and the inclination, then definitely build your own..! Have a look at the builds on here and start asking questions / thinking about your own design. Off the top of my head, for what you're wanting to achieve a gantry style router (not dissimilar to mine) using 20mm alu plates and extrusions should serve you well. Go for a twin ball-screw on the axis which drives the gantry (usually the Y) - this introduces a bit of complexity regarding set-up later on, but means that you can dial out any racking/skew. I'll be up-grading mine to a twin-screw on the Y in the not too distant...

Of course, gantry style machines at this size aren't going to be anywhere near as robust as a smaller fixed gantry style machine, but they're OK and will probably be fine for what you're going to be doing (unless you're trying to make hydraulic components for aerospace, which I doubt :) )

Don't buy anything until you're equipped with a grunt approved plan, especially electronics.

It's a great journey, you'll learn a lot (if you listen to the guys on here that know what they're talking about..!) and you'll forever have something to occupy you in your spare time.

Wal.