The laser is still working fine, 3 years down the line now but the tube was made in the USA not China so that may make a difference.
Cost is impossible to answer - I try to buy things as available, sometimes second user and shop around for the best prices.
With a laser, some wood cuts better than others but a number of suppliers now stock laserable plywood, mdf and others which should cut well but you will always have a blackened edge.
This forum has a number of members using lasers to cut wood, generally mdf, and from the pictures you can clearly see the blackened edges.
http://oplaser.co.uk/opsupport/The best place to look for motors and controllers would probably be ebay but beware that some of the stuff (not all) from China may be less than good quality.
To start with I suggest you look for parallel port connection, you can always upgrade to usb (external motion controller) at a later time.
Tweakie.