Here’s a quick list of hardware you need to build this puppy. In addition to the items listed below, you need a network connection (network cable or USB Wifi adapter) and video display (HDMI cable, HDMI-to-DVI adapter, or Analog Audo/Video cable). A USB Keyboard and Mouse are optional, as most everything can be done via ssh.
(Optional) $7.00 - Pi 3 Model B case
https://www.newark.com/raspberry-pi/raspberry-pi3-case/enclosure-raspberry-pi-3-mod-b/dp/77Y6518
Pi 4 needs a different case.
https://www.newark.com/raspberry-pi/pi4b-case-red-white/official-rpi-4b-case-red-white/dp/07AH6165
$35.00 - Pi 3 Model B+
https://www.newark.com/raspberry-pi/rpi3-modbp/sbc-arm-cortex-a53-1gb-sdram/dp/49AC7637
Better still, get a big ’ole Pi 4 with a massive 4GB of RAM! (Requires different power supply, see link below.)
https://www.newark.com/raspberry-pi/rpi4-modbp-4gb/raspberry-pi-4-model-b-4gb-rohs/dp/02AH3164)
$6.28 - 2.5amp USB Power supply
3amp USB-C Power supploy for Pi 4
https://www.newark.com/raspberry-pi/sc0218/5-1v-3a-usb-c-psu-us-black-rohs/dp/03AH7034
$5.99 - 32GB microSD card w/ SD adapter
https://www.newegg.com/Product/Product.aspx?Item=N82E16820231577&cm_re=gskill_class10_sdcard_32gb--20-231-577--Product
Total cost: $54.27 (excluding shipping)
Next step: Setup