simon johnson said:
PHP Library is a legitimate term, so the .net is definitely worth something. htmllibrary isn't a well known term and is probably worth close to $0. If it was html-template-library or something with reference to html files then that makes sense.
I do not agree with simon johnson. The term HTML has appeared much earlier, than PHP and with it are familiar much more people than with PHP. All 4 domains very good also correspond to their extension. To estimate them I can not yet but I think, that reseller the price much more reg fee.