You'll find that the 4000 still to this day has a lot of support going for it. "aminet" is your friend -- you'll find more software there than you can play with in your lifetime.
While you can add a network card, or 3d accelerator, or PowerPC accelerator card (or 68060 accelerator) *those* are pretty hard to find (most die-hards won't part with them). If you already have those components, consider yourself lucky!
The A500 is also a great little machine for games, and are usually somewhat cheap. 1986, an Amiga 1000 (big brother of the A500), and a copy of Defender of the Crown and I was **FLOORED**. Both software and hardware were years ahead of their time.