You dont need the laser module blanks (3rd item)
You should get 4 850nm Lasers each with a line generating lense
The output depends on the size of your table/setup i have used 10mw lasers which are just about powerful enough but in hindsight i would have perhaps gone for 25mw, (price was my enemy!)
As for a power supply, RS, maplins, etc all do 1000ma adjustable voltage supplies which can be set to 3.2v(have a range typical 3.2v upto 15v) this would be suitable to run all four in parrallel. Its probably cheaper to buy an adjustable supply than a fixed 3.2 at 1000ma.
Hope this helps.