I wasn't able to activate this plugin with my version of WordPress. I think others were having the same problem based on the lengthy discussion here: http://wordpress.org/support/topic/plugin-shopp-wholesale-plugin-could-not-be-activated-because-it-triggered-a-fatal-error?replies=40. This is a beta release, however, so hopefully we'll see an updated plugin! In the meantime, I ended up writing my own client-side solution, which everyone's welcome to use! Here are the details and code: http://www.fredmarion.com/how-to-enable-wholesale-pricing-with-the-wordpress-shopp-plugin/.