I find it really expensive for a few pieces of plastic.
The problem is those RepRap parts take a couple of hours to print.
Have you seen these:-
http://www.emakershop.com/browse/printed-parts
The other parts are just threading an nuts and bolts.
The stepping motors are the most expensive part and they will be needed what ever system you get.
Also look at the repstrap builds on the reprap website.