I´m building this too. Here are a couple of links that can be of use.
Cavegods own thread: http://www.eurobrick...opic=37258&st=0
Dr.Daves build: http://gimmelego.blo...-ucs-at-at.html
If you don´t have a couple of 10030 UCS Imperial Star Destroyers lying around, the LBG 3961 is going to be tough.
The LBG 2489 will also be a challenge. There are some other parts that are starting to get expensive, but I think the two mentioned will be the hardest to find.