I paid < $300 for mine on eBay.
The crazy thing is that like the podcast segment that spawned this, there's SUCH a huge variety of modern hardware to augment them.
I have a 1MB RAM expander board in mine, which I leave disabled most of the time for compat reasons, but there is modern software that utilizes the extra.
Also there's the amazing #fujinet project - It's a device that plugs into the Atari's SIO (serial IO) and puts it on your WIFI lan.
It's stunning how well engineered these old machines were, they treat the net connection like a moden and remote file stores like floppies :)
And that's part of the fun I think as well. Being able to appreciate how these guys in *1982* engineered hardware and operating systems that can still be useful and fun (to some of us anyway!) today.