It depends on what you call inexpensive and how much RAM you want. Go used servers with RDIMM ECC if you want a lot of memory. Price out ECC UDIMM, This goes in lower end servers and Ryzen types.
DDR4 is where you want to be. DDR5 UDIMMs are $$$, if you can even get them.
Your physical location matters as most of us post like you are in USA.
Resources List including Detailed Hardware and System Build Notes (plus new user advice / help)
