I have a beurea full of LEGO parts. All manner of parts. tracks, hingest, parts I've never sen anywhere before. My son and I made almost everything we could imagine. We started making some cars I wish we had glued together. I hit tag sales, and purchased small garbage bags full of LEGOS. I would look to see if they had the odd little strange parts, and picked up many bags for $5 bucks. Those bags retail would be $75 bucks. If you are into LEGO, hit yard sales that look like they had kids stuff, and you won't believe what you can find for almost nothing. A lot of the parts I have are discontinued. My son has 4 huge LEGO models, my Mom purchased him the kits. Those kits cost over $125 bucks, so my son has them on his shelf, and doesn't let anyone touch them. You can't find those kits anymore. If you Google custom LEGO models, you'll be shocked by the vehicles, and ships people make. My only beef is that they will not make one part that would revolutionize LEGO. I've talked to them about it, even sent them CAD drawings, I don't want any recompense. That part is a single layer block with pins on botch sides. This would allow you to make models not only from the ground up, but mirror imaged. They have stated they will take no design considerations from anyone. That really turned me off to that company. Such a simple piece, that would change the way LEGO models could be made. What a bunch of Maroons. Still like their stuff though.
This is the part I proposed (not to scale):