Considering buying a cheap but new wheel, dismantling and rebuilding before ploughing into expensive parts…
I wouldn’t bother doing this, unless you need the cheap wheel anyway.
Read the book through (or at least have a through scan) but properly read each section of the wheel building process as you go, have the book open next to you. There’s a lot in there, nicely laid out in a sensible order, and even if you’re certain you’ve got a new question, not answered in the book and email Roger, there’s a very good chance he’ll tell you which page it’s covered on!
Better practice building with stuff you’re planning to build with rather than cheapo stuff, and cheaper too, as you’re only buying once. You can always practice lacing and dismantling seveeral times, you’re not going to wear anythign out.
There’s a limit to how much damage you can do to new parts, even expensive ones. Go slow, read and follow the instructions closely (I’ve wasted plenty of time thinking I know this bit and missing important bits – like making sure you label the spokes properly – front left, front right etc 😳 ) If it starts to go wobbly in the tensioning stage don’t forge ahead and try and pull it back, back it right off and start again.