A couple years ago I ordered a bunch of components for about a dozen builds, most of them from Tayda but also some bulk stuff from Mouser or Digikey (I forget which). I calculated an average of $22 per build. Cost may have gone up last year though.
That doesn’t take into account the initial costs of buying an iron, solder, various pliers and wire cutters, solder sucker, vises and such, etc., but those startup costs get amortized over a long period of time.