"Apparently, the rule of thumb for online sales is that 5% of your online visitors can be turned over if you have a really sweet offer. Given that we have roughly 5,000 visitors on our site per day, and we put the sales button on every page, the maximum we’d sell is 250 packages a day."
I think they're in for a shock. 5% sales conversion on random traffic to your blog? That's probably off by an order of magnitude. Random visitors aren't in shopping mode. Ask anyone who's ever got a bunch of traffic from Digg or Reddit.
You're lucky if 5% click the link to go to your sales page.