The first one I personally owned was a PowerBook 5300c (still own it - center-right in this photo:
https://i.imgur.com/bqv7L5xh.jpg ) I got it while in college. It was my dad's but he won a MacMall contest and got a brand-spanking-new PowerBook 1400cs, so he handed down his 5300c.
I had used Apple products much earlier (all the way back to an Apple ][+ in school,) and there had been Apple products owned in my household, but that was the first one that was firmly "mine." The first Apple product I paid my own money for would have been a used SE/30 a couple years later, bought out of nostalgia (and the beginning of my collection.)
The first Apple product I bought brand new would likely be either a boxed copy of Mac OS X 10.1 or the license key for QuickTime Pro; I don't know precisely which I bought first. The first
hardware Apple product I bought brand new would have been the first-generation iPod shuffle. The first Apple
computer I bought brand new was a first-generation aluminum 12" PowerBook G4. (I actually bought a refurbished one originally, but it broke hours later, so when I returned it, I paid the extra to upgrade to a new one rather than a refurbished one - front-right in the above picture.) I had owned one or two generation old Apple's before that, (saving money buying used,) but that was my first brand-new.