I built one of these as my first machine.
Use plywood instead of mdf, you will get a much better machine.
Use 200 oz motor, I had 118's just upgraded to 200's, much better speed and power.
The Hobbycnc kit with most of the power supply components is a good way to start if you really want to complete this project.
Get someone to make you/buy UHMW/plastic pipe adjustment mounts, one of the guys here is offering these, I may be making these also mostly because I am cutting alot of UHMW and have small pieces I need to do something with. Again, I just upgraded my machine, much better adjustment.
The material list with the plans is pretty complete.
Use self locking (nylock nuts) instead of regular nuts.
Buy the bolts and hardware in bulk from someone like Enco.
www.use-enco.com
Use 1/2x10 acme rod, again one of the guys is making zero backlash acme nuts at reasonable cost.
I could go on, many good ideas in everyones builds.