You need to add the cost of your time into sourcing those parts, assembling it all, troubleshooting issues and then any long term warranty issues that come up.
I got a warranty, yes. I live in Australia, so there's a government-enforced 2-year minimum warranty period for durable goods such as electronics.
PS: I once worked on a project where 10 consultants sat around burning money for over a month because the customer couldn't figure out how to spin up a lab environment. We walked down to the local computer shop across the street, ordered the beefiest Xeon workstation tower we could build, packed it with drives, put VMware ESXi on it, and then the work could finally start. The "research, ordering, build, and troubleshooting" took half a day. It saved hundreds of thousands of dollars of lost time and money.