Even 5 years ago, I was still grabbing the occasional iMac G3 locally in the $20-50 range, or even thrown in free on more than one occasion.
They've really gone up, though, especially for some of the wackier ones like Flower Power(which no one wanted new).
I remember when they were the big thing on the market, and using them at school, but finally getting some of my own dulled the luster a bit for me. The early ones(with a tray loading CD drive) have fragile plastic like a lot of other Macs of that age and are prone to bad flyback transformers. If you want to use them, the tray loaders fall into a weird firmware range that has frustrated collector-users for years. Not to ramble too much, but the older beige Macs(anything with a serial port, internal floppy, and ADB connectivity among other features) used a "big ROM" design that we usually call Old World ROM(OWR). "New World ROM" computers generally have built in USB ports and no legacy ports like serial or ADB, and use a different-much smaller-ROM philosophy. Still, though, the earliest NWR Macs-the iMac G3, the Blue and White G3 tower, and the Lombard PowerBook, are all technically NWR Macs but with some OWR features(the B&W tower has an ADB port, the earliest iMac G3s had a fully functional serial port buried in them for the IRdA unit on the front, plus also had a floppy controller) and a lot of the firmware quirks of OWR Macs. They can be a nightmare when you're trying to go outside the box.
The later slot loading CD drive iMacs(which came in a ton of different colors-the tray loaders were originally Bondi Blue, followed by the "5 Flavors" of grape, tangerine, strawberry, blueberry, and lime) had a lot of upgrades to like. They used largely faster CPUs, most had Firewire for fast external connectivity, held more RAM that was easy to upgrade, could be fitted with WiFi, and also had phenomenal speakers even by todays standards(until they start to rattle). BTW, most slot load iMacs officially support OS X 10.4.11, where the tray loaders top out at 10.2.8, although I generally stick to OS 9 on G3 CPUs. The big issue with the slot loaders was that they had no internal fan, so if used heavily could cook themselves-the heat isn't exactly kind to the flyback either, although I seem to run into fewer issues with them than I do tray loaders.
Can we also mention the ergonomic nightmare that is the original iMac keyboard and mouse? The keyboard isn't terrible, but is rather small for my taste. The mouse is just-bad. I hated them 20 years ago when I was using them in school, and I still hate them as a collector with drawers full of them. I pull one out occasionally thinking it can't be all that bad, but then connect it and remember that yes, in fact, it can be that bad. I only keep them around so that I can have a matching correct puck mouse for display, or to let someone else have the "authentic" experience. At least Aple realized how bad it was themselves when they released the wonderfully ergonomic(still, even in 2023) optical Pro mouse and started shipping it with everything not too long after.
At the end of the day, though, you can definitely tell that they were a budget minded computer. When I use CRTs these days, I almost never use anything but Trinitron or Diamontron aperture grill CRTs, and I can't get around how fuzzy a shadow mask like the iMacs looks no matter what you do to the resolution. I still use OS 9 a lot, but mostly do it on G4s. In particular, on a G4 tower, I can get a lot more RAM, a better graphics card, and a lot more storage(plus options for how to configure it, including relatively easy ways now to put solid state drives in) and it all runs cooler. It's all the experience of an iMac G3, but just faster and and overall better. A set of HK Sound Sticks look right at home and are better still than the iMac G3 speaker. You can even enjoy a modern display, although most GPUs compatible with G3/G4 towers will top out at running 2x 1920x1200 displays, and depending on the card even running a single 1920x1200 may be pushing it. There are a few cards that work in AGP G4s that have dual link DVI and can run two 2560x1440 displays, although those are OS X only cards(and they aren't plug and play in the computer-they need some modification). I should maybe take that back as I'm not sure there are any G4 compatible dual dual-link cards, but you can definitely run one 2560x1440 and a second 1920x1200 on a decent number of cards.
