I started with an X8SIL, 8GB of DDR3, and a SUPER cheap X3430. With eBay discounts I came out to about $48 USD/ $65 CDN.
Managed to find a Thermaltake core P5 for $65 CDN. PSU I sourced from a used computer, and CPU Fan I found on Amazon for $17.
Total at this point is under $150 CDN or $110 USD.
I found a 1TB SSD for $129 CDN (waiting on the 16TB deal to ship!) and installed a copy of Server 2019. Total hardware cost comes to $280 CDN / $210 USD until I can add some real space to it.
The downside I guess is that the power supply cable is not long enough for routing through the back, but for not having to worry about buying one I’m happy for now.