They still have the original sets that come with guides to build many things out of the same set of bricks, and a box to put them in. These are the best ones to

They still have the original sets that come with guides to build many things out of the same set of bricks, and a box to put them in. These are the best ones to get kids just starting out. Plus the lego stores have pieces sorted in buckets like a candy shop, you buy a container and fill it up with whatever you want. I've never used it, but the website lets you choose from 1400 different bricks https://www.lego.com/en-us/page/static/pick-a-brick https://www.lego.com/en-us/page/static/pick-a-brick The Sets will sometimes have a unique piece or two, but outside of the mini figs it is way rarer than you might think. And as others pointed out if it's unique now it doesn't mean they won't find a way to reuse it later.