Updated to work on 2.3.3.2 and above.
Although I tested it only on 2.3.3.4 - I presume this should work on all 2.3.x.x.
Based on the original addon http://addons.oscommerce.com/info/3798
Which was based on version adapted for Separate Pricing Per Customer is based on the Quick Price Updates (http://www.oscommerce.com/community/contributions,122) version 2.6 of February 2005. The "only" additional feature is that you can choose a customer group and then the prices for that customer group will be shown and then be changed.
All credit to original authors.