Hi all, first post.
I, too, have begun collecting parts for building a UCS Millennium Falcon. What have I gotten myself into?

I've wanted it since it came out but could never justify the $500, but looking back, I'd gladly pay that.
So I went to Bricklink and parted out the set. I had my wife paste that huge list into an excel sheet (I have no idea how to use excel... I'm an artist, haha). She modified it so I could keep track of how many of each part I have left to buy. Next, I went through all of my (and my son's) bins of Lego. I'm sure I cannibalized some of my old sets, but none of his. I came up with about 800 of the necessary parts this way.
Then, I hit up a local used toy store that lets you fill up a gallon-sized Ziploc bag from their dozens of Lego bins for $25. Got another 500 pieces out of that (and a fair number of the rare ones), and I will be going back.
All in all, my spreadsheet tells me I currently have 1339 pieces. The amount of sorting and indexing and then deleting items I have from Bricklink is ridiculous. The actual build of the ship is going to be child's play once I've finished collecting and sorting everything! But a quarter of the way there on $25 isn't too shabby, either. And I'm not going 100% on the exact colors; there's a good bit of expensive pieces in rare colors that I don't have to have. I'm not planning on reselling it anyway.
Finally, here's how I'm going about indexing everything. Don't know if it's the best way, but it was the best I could come up with:
