It started at $35/unit, in the United States at least. I've still got the invoice for my 256MB Model B...

$35 today gets you a 1GB Pi 4 Model B. For somebody who actually needs the form factor, it's pretty much a fine value.

For somebody who wants a server, it's always been a weird choice. (sorry Jeff :D )

For somebody who wants a desktop, the Raspberry Pi 500+ was a really fun choice when I bought mine in January. They cost twice as much today, which is sad. (although if anyone is feeling the desire and lives near a store, Microcenter has them on sale for $100 off...)

The entry level option is the Raspberry Pi Zero 2 W, which is still $15

https://www.raspberrypi.com/products/raspberry-pi-zero-2-w/

It also has twice the RAM of the original Raspberry Pi (at launch), plus WiFi, plus a lot of CPU power, and a powerful GPU, and a lot more.

I have a 16GB model and I use that much RAM for some specific development work on the Raspberry Pi platform, but now I wish they had never announced the 16GB model. It has created so many complaints from people who shouldn't and won't be buying it.

It depends a lot on your use case. For headless stuff (automation that mostly uses the GPIO, for instance, or running a few "old school" server processes), you usually don't need that much RAM. However, when used as desktop computers, 8GB becomes the bare minimum to run a modern Web browser with a few tabs...

Someone said 640kB is enough for everyone.