I wouldn't say I was ever a serious collector of Transformers toys, despite being in over the deep end with the series. Back when I was in my mid teens, had a job and a lot of disposable income since I had nothing to pay for, I collected the entire first wave of the RiD figures, and the Transformers Armada toys. I also bought a bunch of the G1 Japanese reissues of the characters that I liked.
I stopped "collecting" Transformers on a regular basis when I went to college when I was 19 or 20 (can't remember which). Plus, my then wife was my girlfriend who I was in a long distance relationship with, so I saved my money all the time for flight tickets so we could be together. Since my wife and I have been going to Auto Assembly together, we buy a couple of Transformers here and there over the last few years, but the lack of space in our apartment means I'll never collect a whole wave, or series or anything. Most of my Transformers collection is still at my dad's house!