Where can you get a workstation like that for $2,300? Is that building it yourself out of parts? Last time I looked into getting a machine like that it seemed to cost more like $4,000+.

Self-build can easily meet those specs (minus OS + monitor + peripherals).

Example $2333 build: https://pcpartpicker.com/list/t4FjZZ

$2300 is a reasonable estimate if he builds it himself.