That rails could be good for a month, but will need constant tweaking later. Its a better solution than roller bearings or V rails but... I dont know how you value your time but when actually working, any hit and miss day will cost you hundreds of $$$ missed profits.

My opinion again is to buy used machine, some times people from forum sell good ones. or pay sb to do it for you and start making money from day 1. Yes i build my machine, but it was a do-all-extraordinary and if i have to buy similar i have to pay more than 20k for it so there was a reason for the wait. But for pure woodworking, i wouldn't think twice and buy even Chinese, so to start making money faster