All dollar ammounts are listed in USD.
http://www.mantisbt.org/ Mantis - Free
http://www.bugzilla.org/ Bugzilla - Free
http://www.pikoni.com/Track'em - $200
http://atlassian.com/software/jira/ Jira - $1200
http://www.techexcel.com/products/devtrack.html DevTrack - Unknown