openbsd is freely available in various ways: the source can be retrieved by anonymous cvs, and binary releases and development snapshots can be downloaded by ftp, http, and rsync. prepackaged cd-rom sets through version 6.0 can be ordered online for a small fee, complete with an assortment of stickers and a copy of the release's theme song. these, with their artwork and other bonuses, have been one of the project's few sources of income, funding hardware, internet service, and other expenses. beginning with version 6.1, cd-rom sets are no longer released.