For the default (logged in) shopper group have you selected to use shoppergroup specific price display? If so then chack those settings.
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VirtueMart 3.0.18
Joomla! 3.6.2
Did you miss the vital security releases?
https://www.joomla.org/announcements/release-news/5678-joomla-3-6-4-released.html
https://www.joomla.org/announcements/release-news/5693-joomla-3-6-5-released.html
http://forum.virtuemart.net/index.php?topic=118683.0