You can sell unsorted lego by the pound (on Ebay they will fetch ~$8/pound), if there are no minifigs or special bricks. If you have minifigs or special bricks, and are willing to pull them out and sell separately, you'll make much more.

Prices on Craigslist in higher cost areas tend to be higher, as usual. If you live in a higher cost area, buy on Ebay, sell on Craigslist.

> some parts are worth more than you’d think reasonable...

all parts are worth more than I’d think reasonable.

You are entirely entitled to your own estimation of the value of lego parts, while I would agree that lego is in an absolute sense way too expensive on a relative scale it is cheap compared to most other toys given the amount of use it gets. The only things it really competes with are musical instruments and digital gizmos.

I am surprised at the cost of LEGO parts, but they are undeniably good and durable toys.

In original packaging maybe, but not after several kids have played with them for years (and inevitably lost pieces)

There's a cottage industry of people sorting those piles of lego and then completing the sets from parts bought individually. It's not going to make you millions but there are people that do this relatively successfully.

Bricklink is a fantastic resource to replace missing pieces.