There are some key ingredients that set one LEGO set apart from others when talking about "investment potential." Why does one 800 piece set triple in value in two years while another 800 piece set stay around MSRP? Is it the individual theme difference? Piece difference? Minifigure difference? What do you look for in a set that makes it a worthwhile investment set?

Now I know some of you

I think you have already mentioned a lot of good attributes in some of the other pieces you've written. For me, I just go with my instinct on what I think people will think is cool later. I think I'm basically just a big kid, so I feel like I've always had a good idea of what both kids and adults will like. For me, it doesn't matter how many pieces or from what theme a set is from as long as I think the set is awesome. Exclusive minifigures can help, but if a set only relies on this and then the same minifigures show up in another set, the set won't go anywhere. A perfect example of this is 7664 TIE Crawler. The Shadow Troopers were exclusive to this set so I thought it would make up for the lackluster model. However, the Shadow Troopers later showed up in the 7667 Imperial Dropship battle pack and gave people no special reason to want the Crawler. Going with your gut can cause you to miss things too though. I never liked 10196 Grand Carousel so I skipped buying it. Of course now I wish I had grabbed a couple. Like anything, it's easy to look back and say "I should've bought more of this or that." I always have a hard time with this part. I knew Cafe Corner would be big when it was done, but I don't think I expected it to do quite as well as it has though. I think about how many of these I looked at and left sitting on shelves, always wishing I had grabbed quite a few more after it was gone, even before it reached its current levels. So I guess my advice to myself, and anyone else who cares, is to not dwell on the missed opportunities and try to focus on maximizing future ones.

I go a lot by the cool factor too. Another factor I like to consider is if lego promotes the line through tv shows. Obliviously Star Wars and Ninjago are doing quite well. A new set is introduce on the shows which leads to demand for the new set.

I think you have already mentioned a lot of good attributes in some of the other pieces you've written. For me, I just go with my instinct on what I think people will think is cool later. I think I'm basically just a big kid, so I feel like I've always had a good idea of what both kids and adults will like. For me, it doesn't matter how many pieces or from what theme a set is from as long as I think the set is awesome.

Exclusive minifigures can help, but if a set only relies on this and then the same minifigures show up in another set, the set won't go anywhere. A perfect example of this is 7664 TIE Crawler. The Shadow Troopers were exclusive to this set so I thought it would make up for the lackluster model. However, the Shadow Troopers later showed up in the 7667 Imperial Dropship battle pack and gave people no special reason to want the Crawler.

Going with your gut can cause you to miss things too though. I never liked 10196 Grand Carousel so I skipped buying it. Of course now I wish I had grabbed a couple. Like anything, it's easy to look back and say "I should've bought more of this or that." I always have a hard time with this part. I knew Cafe Corner would be big when it was done, but I don't think I expected it to do quite as well as it has though. I think about how many of these I looked at and left sitting on shelves, always wishing I had grabbed quite a few more after it was gone, even before it reached its current levels. So I guess my advice to myself, and anyone else who cares, is to not dwell on the missed opportunities and try to focus on maximizing future ones.

So true. Go with your heart as they say. It doesn't hurt if the set has 2000+ pieces either. Almost every large set appreciates better than smaller sets, or so it seems. Don't get me wrong, there are plenty of small sets that kick @$$, but the it is easier to resell one large set, than multiple smaller sets.

I look for sets that have an iconic value, especially those which apeal to AFOLs. For example the star wars Millennium Falcon over say the Republic Frigate. The Black Pearl over Whitecap Bay. Sets like the Batcave, Batmobile or even Boba Fett's Slave1 are things that may appeal to an AFOL or perhaps even a non Lego person who really likes Batman or Boba Fett. Modular sets are excellent because people want to collect them all and thus the price rises from demand. A good example of this was the Ninjago dragons which spiked in price as people rushed to collect them all. For instance in Nov.2011 I bought 4 Ninjago Ice Dragon sets #2260 from Target for $15 each, and turned them five months latter for an average of $85 each. I also don't discriminate when sets go on cleareance. If its on sale for P off or more it's already likely a good investment, even if it's Spongebob. I agree with others who say to use your instinct, if it's cool to you it will likely be cool to others people.

I ONLY get sets that I like and would want to build. Thankfully I am not a big collector of minifigs as that seems to be a key factor in many AFOLS getting sets that they would ordinarily never get. Good example would be the Gungan sub (9499) just to get Queen Amidala, who was not even in that scene in the movie!?!

I think one of the great things about LEGO, as far as I'm concerned, is that discontinued sets do not lose value over time (assuming they are MISB). The only one I can think of is that Twilight Star Wars set, but that's not surprising; the set was a mess haha. A set no longer in production will at least sell at its retail price, so in this sense there no bad investments per se, but there are undoubtedly better investments than others. I think it's important to keep in mind how long you are willing to hold on to a set before selling. You may have to wait several years for certain sets to start increasing in value, while others will shoot up in price immediately after they are sold out. The sets geared towards AFOLs are the safest bets in my opinion. They usually have the best price per part ratio and simply look the best. Adults are also the ones who can afford to dish out large sums for sets they missed out on. With that said, I often find myself doubting the potential of a set. Amazon had a great sale for the Imperial Flagship (10210) right before it was discontinued, and I tentatively only bought a few thinking it would take a while to increase in value. I was wrong and wish I had bought more. I guess you have to just go for it once in a while.

You can never go wrong with sets with lots of mini figures and pieces. I'd rather sell one large set and ship one time, then sell 4 smaller sets, make the same money and have to package each for shipping.