Public domain TeX software on electronic media will typically be priced to recover the cost of packaging and distribution. The user may also be requested to honor shareware fees for some items.
For information about product availability or cost, contact the specific site listed.
The TUG store stocks the current TeX collection on DVD for various systems -- Unix, MacOS X, Windows (based on MiKTeX) -- as created by a collaboration among several TeX user groups and numerous volunteers. This collection features load-and-go binaries for most supported platforms as well as an up-to-date version of LaTeX and an extensive collection of packages organized according to the standard TDS (TeX Directory Structure).
TUG may have information about where to obtain electronic distributions for other systems not listed here.
For users outside North America, TeX groups in other regions also distribute the TeX Collection as a benefit of membership, and may have extra copies of the DVD for sale. Information about other TeX groups can be found on this web page.