My first PowerPC Mac was also the first Mac that was "mine", rather than a Mac at school, a Mac my dad brought home from work temporarily, etc.
A PowerBook 5300c. It had been my dad's, but he had just upgraded to the then-brand-new PowerBook 1400cs (he won it from MacMall,) so he gave me his 5300c. I was in college, and was already the only one there with a laptop (an old black-and-white 386 that I then gave to a friend.) I still have it. (Although it sat in a closet for quite a few years after college, and before I started collecting Macs.)
Then, around 2000, I started collecting. Most of my PowerPC systems are currently in storage, and are beige 7x00 systems I got from various people who were retiring them from active use between 2000 and 2002 who knew I collected Macs. Likewise with a few more PowerBook 5300s, and a couple 1400s (including the one my dad had upgraded to.)
In 2001, when OS X came out, I decided I needed an OS X capable machine, so I bought a used beige Power Mac G3 tower from local reseller PowerMax. Later I got a first-generation iMac used, too, as a "play machine."
In 2003, I sold both of those, plus my main PC, my "workstation" PC, and my PC notebook, all so I could get a brand-new 12" PowerBook G4. It was the first brand-new Mac I had ever owned, and only the second time I had ever bought a "ready to use" computer brand new. (My PC notebook purchased in 1999 was the other - every other computer I had ever owned had either been purchased used, or was a PC with parts I bought separately and assembled myself.)
Later, in building my "collection", I ended up getting another beige G3 tower for free, as well as another first-gen iMac.
Of my "collection" machines not mentioned above, most were bought used for small amounts of money. iMac G4, Power Mac G4 Cube, PowerBook Duo 2300c, Power Mac G4 "Digital Audio", etc. A few I received free from people who knew I collected (B&W G3, another iMac G3, a couple Lombard PowerBook G3s.)
When I was running a small business, I bought an eMac to be the business machine - only my second brand-new-Mac ever, and my first-ever brand-new-name-brand desktop machine.