If you absolutely need a single 4116 16kbit DRAM chip right now (well, in several days) eBay is the place.
Either internal components, or people parting out a broken system, you can find it all.
Need one screw for your iMac? It’s there.
Need some random resistor size? You can buy 1000. In through-hole or different SMT sizes.
Need a power supply for a particular TV? It’s there.
Need a USB male to male 4’ cable? It’s there.
Need a 5V to 18V 2A power supply? Etc.