Initial Price: US$795, $2,487 in 2020
In 1980, the 4000-series PETs were launched. They came with BASIC 4.0, which added commands for disk functions. With this series, Commodore discovered that people were buying cheaper 8 KB and 16 KB models of the 3000-series and upgrading the RAM rather than paying extra for the 32 KB model.
This particular unit has been upgraded to 32K RAM and it was used at some point in a middleschool, Lake Forrest Academy Illinois.
Upgrade from 8 K RAM to 32K
My upgrade was pretty easy as this unit had empty sockets on the mobo. You can see the more recently added modules, the 4116 memory chips, that are higher in contrast.
I recently discovered that I was lucky to have this mobo revision, cause most of the 4000 series you find have no slots or punched out mobo to fit the memory, so people go for option #2, The Future Was 8 Bits solution. I find it a bit overkill and flashy, but it works extremely well.
Above solution was provided by Reddit user frederic_stark. He also sent me a picture of his mobo that looks completly different from mine.