For me, the question of "retiring" hinges, perhaps appropriately, on age. I've past 40 now, and I'm cognizant of the fact that I'm entering a phase of life when sudden health catastrophes or necessary surgeries are not entirely unheard of. It's a bit irresponsible to keep growing this collection and never consider the burden unloading it could be to family members (or even to me, were I to become permanently handicapped or incapacitated). So thinking about no longer buying Transformers and liquidating the collection is something roaming around in the back of my mind now, where it wasn't before, just because I don't want to saddle my wife and parents with the task of getting rid of all this, or paying someone else to do it (which I'm sure would be the option they'd go for). By no means do I ever consider not being a fan anymore, or even buying a new figure here and there, but I feel my days of collection-building are coming to a close in the next ten years. We'll see how I feel at 50.