Several people have asked me recently what hardware I would buy today for use as a home firewall.
for a total of $176, including shipping. Links were accurate as of October 22, 2018.
This gets you a tiny box, similar in size to random commercial house router/firewall/wifi access points, which can run a standard Linux operating system with a complex firewall running at 1 Gb/s in and out, more RAM than strictly necessary, and an SSD which is both very large (and therefore can last a very long time) and boot the system quickly enough that you can do a reboot without losing TCP sessions.
I would also recommend a medium-sized USB thumb drive to set up as an emergency booting and backup device. Call it another $15 or so.