I suggest no virtualization for that arrangement.
i3 has not that much core number, so the overhead of a virtual environment could impact a bit more than other CPUs. I stand by Andy for “more ram”, but if you have to choose between 8 bullet-proof gigs and 16 cheap ones, better 8 (2x4gb, hoping that your mainboard has 4 slots).
If available, look for an i210 network card. Except business oriented brands PCs, lots of mainboards have Realtek NICs, when lucky. Which are not nice on CPU consumption and data transfer; Intel ones are often faster and less CPU-demanding. If in budget costrain, use Intel for GREEN zone and others for RED/Orange/Blue/whatever
Don’t forget the backup!
Don’t go crazy first, a not brand news USB drive of 500gb could be nice as starter, but allocate time and effort for evaluate the drive status and consider to buy a new one “soon” (end of 2022).
Consider the quality and the destination of the hardware. An efficient PSU will allow you to have less issues and lower power bills, a reliable “business oriented” mainboard will serve you a bit better thant a gaming-oriented one with bells and whistles.
Also, consider AMD Ryzen as an alternative. The core count increase, the advantage for faster ram increase, most of the recent CPUs provide PCIExpress Gen4. Which will allow you a massive boost on storage in the future with NVMe cards. With a Ryzen 5 3xxx CPU Proxmox become a much more interesting option. If considering AMD, Bxxx chipset is the minimum, and Xxxx are not that interesting as server environment.
Last hint: the second hand market is flourishing of used “server” hardware. Maybe you’ll find DDR3 only, and old CPUs. But reliability of that kind of hardware is much higher than business PCs. Which have higher reliability than custom builds (most of times).
The price to pay is higher noise, higher power demands and often higher price for spare parts. But several companies will allow you to subscribe hardware insurance on server-level hardware, not on custom builds.