There’s some confusion on the pricing. This should provide some direction
If your SharePoint site is external facing and the end users authenticate with active directory, then the Office SharePoint Server 2007 for Internet sites license is not required, thus saving you $40,943.
So if you have 30 users which authenticate with the site infrequently so there are perhaps 10 concurrent users, the standard CAL is only needed. So the total cost is $94 per user.
Office SharePoint Server 2007 @ $4424
10 concurrent users @ $94 / user $940
Total in software costs is $5364