Here's the latest on season 4, from a Vulture interview with show creator Mitch Hurwitz:
For every other possible season 4 detail, click here.
Structures include the Bluth home, the Bluth Company stair car, and the banana stand (money presumably not included).
The stair car is currently up for voting on Lego's crowdsourced idea site, Cuusoo, and could be turned into an official Lego set if it gathers enough votes and meet the approval of Lego's design jury.
Meanwhile, it's probably safe to say that the Lego version of the Bluth house is better-constructed than the real thing.