I don't really "collect" anything per se, but I keep what I do get...for a lifetime!
My first ever stuffed animal I received as a newborn now sits proudly in my daughter's room with her stuffed animal collection.
My very first car is still with me (though not running right now. When time (and money) become more available, my daughter and I will resurrect it to its former glory. But while I did the car show circuit, I did start collecting trophies.
My home music studio isn't state of the art, but it looks impressive because I still have (and use) most of the dated hardware that I own. I do get a new piece now and then, but when added to the existing bloated collection of gear, the studio is beginning to look like a mad scientist's secret lab! :p
My home stereo rack is a collection of components that I could not purchase in its entirety. I bought a Dual turntable in college, and decided that I would purchase each new piece on my birthday. Did that for about 15 years.
I don't consider the MBs a collection, but a coincidence. A "collection" of MBs sounds a bit snooty, and I am so far from that income bracket...