When you think you are running out of space for Joes, consider the poor guy who collects Joes, Transformers and Star Wars.
I used to collect SW, but the prequels drove me away, so I don't bother with that much anymore outside of the occasional figure. I do have a sizable existing 90s collection though. As with Joe, its the vehicles that kill all the space. I actually sold off a ton of obsolete figures and obscure characters last year. I'm considering unloading the vehicles. Even if one only collects SW, I have no idea how on earth completists in that hobby do it.
I am a huge Transformers collector. And since they ARE vehicles, they take up a LOT of room, even loose. Add to that the fact they are all oddly sized, have things sticking out of them, are fragile, etc and you can imagine how difficult they are to store. I have most of them boxed up and even then they take up almost the whole closet. And I'm not even close to completist. I only collect the first two years of G1, Classics, Movie, and certain figures from other modern lines who mix well with those. I only have a handful of Beast Wars/Machines and am skipping Animated. I have fire sales occasionally, and am planning another one soon.
With Joe I have 3 large boxes full of loose figures, and again the vehicles take up all the space. Definately need to lighten the Joe load too, in light of all the 25th goodness coming in.
Overall I have way too many toys and need to severely cut back for my own sanity. Its just too much to keep track of at this point, I no longer have the time for customs, and cant even remember what I have in many cases. I barely appreciate any one figure, as I spend too much attention on managing the whole collection.