The HP T620+ makes an ideal pfSense box. They used to be cheap, CPU is quad core with AES-NI, can take plenty of RAM and have a PCI-e slot for a quad NIC.
Unfortunately since word got out the prices shot up and there are no cheap ones left, at least in the UK. Used to be that you could get one with 8GB RAM and 32GB storage for around $80.
Anyone recommend a decent alternative under $100?