I just stumbled across the site and am very excited about it! I loved Lego as a kid and had a room full of different sets. It has been sitting in boxes in my basement and I just looked through it because I was planning to sell it and wanted to get an idea of what I had. I had no idea the sets are worth so much! I'm reconsidering selling them now of course. I'm sure I'll have many questions as I get familiar with the site but I do have one now: The first set of mine I googled was Lego 5591. I found someone on Amazon asking $650 for a used set with instructions in a zip loc bag (just like mine). But I see on Brick Picker the used price is listed at $93. Why the huge difference? Any insight would be appreciated. Thanks!

First welcome to the site! Second the values of sets in the price guide are taken from eBay data collected from US auctions. As you get more involved with LEGO prices you will see that some people on eBay and amazon ask outrageous prices for their used and new sets. The price in the guide is pretty close to what you can expect to get from the sets. There will always be someone somewhere that will pay a huge huge premium for a set and for various reasons. Most of us here though look to make the most profit possible and in order to do that we look for the absolute best deals. Hope this helps a little.

Well, back in November, Lego 5591 sold for $300 not including shipping. Though it depends heavily on the buyer, I believe that this set is worth a bit more than $50. Here is the link for the $300 listing: http://www.ebay.com/itm/NEW-SEALED-LEGO-MODEL-TEAM-5591-MACH-II-RED-BIRD-RIG-/200846660240?pt=Building_Toys_US&hash=item2ec364d290