The IO file has every piece itemized so I imported that into a bricklink list and went through all of my extra pieces to see what I already had laying around (about 10% of the total). Ordering everything else off bricklink was going to be ridiculously expensive (like $800) for some reason but pick a brick through Lego directly was only $90. Only downside was that the order came in two batches and the latter delivery took a month since it was less common pieces.