Nintendo 64 - First "expensive" product I ever saved up for in high school. Pre-ordered from Toys R Us, yep, in the days of a pull a ticket from the aisle. Sad thing I remember somehow being exactly $50 short when it came to paying for the thing. My dad filled in the rest, but to this day I have no idea how that happened. Exactly $50 short and I counted that case like a dozen times before going to the store.
Dreamcast - Came out on my birthday. That was THE LONGEST DAY OF HIGH SCHOOL IN THE WORLD. On top of that, the Sonic Adventure disc didn't work -- known issue at the time -- but I drove right back to Gamestop to get that fixed ASAP. The killer whale, to this day, is one of my fondest gaming experiences.
Playstation 2 - This came out in my first few weeks of college. I had no intention of buying it (thus no pre-order) but somehow FOMO hit and here I am lining up in front of the Sony Metreon in SF at 2 AM in the morning. First day in line. Missed out. Too late. So come back later that day at 11 PM for the next morning's run. Scored a PS2 and SSX. My buddy bought Midnight Club Racing, which ended up being a great series, but that first game stunk and my buddy was soooo jealous. Side note: Riding the BART back across the bay at 8 in the morning with a giant bright blue Sony PS2 bag and reports of people getting mugged for their PS2s was terrifying. Made it back home. Then realized I forgot to study for an exam that day. Worth it! It was an elective anyways.
Wii - Didn't pre-order. FOMO hit again. I was in Orange County by this time (CA, not FL) in grad school. Camped out at Best Buy in Costa Mesa, CA with about 20 other folks, but only had to wait a couple of hours as opposed to all night. The Wii and I have had an interesting relationship. I think to this day the motion controls have served as a deterrent to my overall enjoyment, so I feel lukewarm about camping out for this thing.
PS5, XSX - I finally have expendable cash in my life. No more messing around. Pre-ordered online.