I've gotten my two teens on the classic episodes of Star Trek once they made the tribbles reference in the last movie. The light bulbs went off.
I think it could easily get outta hand, but like others, I'm pretty frugal. Once I picked up the mech mod, that turned into two RBAs. Now I'm starting to look at other mechs, then more batts, then... aw crap, I'm gonna run outta room.
The other problem is stashing all the new stuff from The Boss (aka wife). Must be what its like to hide shoes.