The Lego Star Wars Millennium Falcon set is a faithful reproduction of the most legendary Star Wars starship; you'll have to make the Kessel Run in less than twelve parsecs to grab one, though.

The 2,314-piece R2-D2 display model was officially retired by Lego in January, so this set was already hard to find.

One of the more impressive and enduring LEGO sets for adults (well, ages 16+, anyway) is the LEGO Ideas Tree House. It's a massive three-unit tree house you can build with either green leaves or yellow leaves for an autumnal feel. It normally rings in at $250, but it's on sale for $75 off for Prime Day. Grab it before it's gone.