Ron Hebben Great suggestion.  Do those pulse or flash at all in the original film?

Jonathan Benaim You buy the assembly instructions from Brickvault, and that includes a parts list which you can then use to purchase parts from individual sellers on bricklink.com. Brickvault includes information about how to use bricklink and order your parts. bricklink is like ebay but for LEGO parts.

Just to set expectations, I checked the prices tonight for the parts needed to build the kit.  The smallest number of orders possible to get all the parts is three orders, but the cost there is $1,100 for the parts not including postage.  You can look for the lowest price, but that produces a total of 13 orders (so higher postage total) and a cost of $522 for parts.  Unfortunately building these MOCs is not cheap.

Jonathan Benaim As Freakmaster says, these designers work very hard on making great models and then putting in hundreds of additional hours to document them and show the rest of us how to build our own.  The instructions and parts list on Brickvault are only $30-- that's an easy investment, especially when you're looking at a premium model like this.

Jonathan Benaim LEGO do sell some parts directly on their website, but many of the parts in this set are either out of production or in colors that are out of production.  In these cases, LEGO would not sell them.  Also, in 90% of the cases, Bricklink is less expensive that going through LEGO itself.