I have a couple of lamps similar to this, with the clamps, etc. I snap them up when I see them in thrift stores. If its one that has a peg on the bottom that fits into a holder that clamps onto the table, they are easily replaced, if missing, with a piece of wood with a hole drilled in it and a C-clamp. I find that my springs never put it where I want it (maybe that's why I found it in the first place???) but I use a shoe lace tied to something overhead or to the side, and just make it work.
https://www.amazon.com/Elucidate-Pow...with+magnifier