All these have decent development potential as Joomla Howto kind of sites, but they are brandable at best and kind of restricted to Joomla as against CMS.
End user values (joomla developers etc) -
joomlacoders.com - $50
joomlaguide.com - $100
joomla360.com - $25
joomladepot.com - $25
joomlapros.com - $25
joomlapro.com - $50
I doubt you'll find many domainers interested in these.
Good Luck