One thing I've noticed is that many of the (secondhand) buckets of bricks we've found are NOT a general purpose bucket of bricks. It seems like half the pieces

One thing I've noticed is that many of the (secondhand) buckets of bricks we've found are NOT a general purpose bucket of bricks. It seems like half the pieces are special-made for a specific purpose. ("Oh, this is a squid-head. This is a custom-made tailpipe for a race car. This is a police-car-top-shell. This is a Gungan head.") I exaggerate, but it's very noticeable when I went to build something with my son this past holiday. Looking at sets in the store (I still ogle them ;)), it seems to match this pattern as well. Granted, you can buy them in bulk, and you can special order ones you need, but ... it seems not quite the same. I'm sure part of it was that the legos we were rummaging through were poorly organized (color? size? vintage?), and could not be used more than one pucket at a time due to spatial constraints. ;) I think that the key may be to buy large-ish sets which have enough general purpose things: plates, angled plates, angled blocks in varying directions, etc, or to special-order bulk collections of things.