Hi and welcome to the forum!

To my knowledge there aren't many, if any, kit builds on here. Most have designed their machine either from scratch or borrowed bits of designs from other builds. Most build logs are almost detailed enough to build the same machine, or certainly one pretty much like it if you're mechanically minded?

For a 1000 x 600 cutting area you'll be looking at an overall dimension of 1300 x 900 (which co-incidentally is about the size of my machine!). For this you'll need 4 off 3.1Nm Nema 23's (I've got 2 x Nema 23's and 1 x Nema 34 for the long X axis) anything less will probably not cut the mustard. These need a healthy dose of voltage to get the best performance. I'm not familiar with the smoothieboard but I'll guess that it's 24V max which means you'll not get enough voltage to give a decent performance.

A 1k budget is stretching it a bit unless you can beg, borow or steal (only kidding!!) bits for your machine. Most builds I reckon come in at around £2,500 using linear rails, 80V digital drives, DIY PSU, decent BOB, good control panel with safety relays etc. etc.