Not sure about psSense, but I use this box to run VyOS [1]:
https://world.taobao.com/item/520967318043.htm
1.8GHz dual core celeron, 2GB RAM, 25GB SSD, wireless + gigabit LAN, fanless and in a nice box with power supply for $100 + shipping.
Disclaimer: No idea how difficult it is to purchase from taobao internationally and this vendor/model may not be the exact one I'm using, but it gives you an idea of the economics that are possible.
[1] http://vyos.net/wiki/Main_Page
