Just venting some 
I discovered today that, for me, the Pre-Pub program and sells are not always the best way to go.
Listed as "New" in the Logos store, the 26 volume Believer's Church Bible Commentary is listed as a regular price of $432.99.
During the Christmas sale of 2011 I bought the available 19 volume set for $299.95. I then ordered the 5 volume upgrade and it was delivered at the end of February 2012 for $112.95 (I can't remember if this was pre-pub or not). Finally thinking that pre-pubs and sales would get me the rock bottom price the pre-pub 2 volume upgrade was delivered in November for $49.95.
My total price for this 26 volume set was $462.85. A difference of almost $30. I think that in the future if I decide to update any commentary sets, I will probably skip the pre-pub part since it is not saving me anything. In fact, dynamic pricing may have saved me some money in this case.
For me to have bought the 19 volume set on sale and at least one of the upgrades on pre-pub, I think it is a shame that buying the entire package at regular price is still $30 cheaper. 
Lesson learned.