There are very few blogs about sales and product configuration, most are written by different vendors and thereby biased, however they are still interesting.
Best blogs about sales configuration:
NovusCPQ – NovusCPQ probably has the best general blog about CPQ right now. They are a consulting firm supporting companies with CPQ competence.
KBmax’s Blog – KBmax is one of the smaller vendors but they do probably have the most fun and interesting blog.
Tacton’s Blog – Tacton also has a well written blog about sales and product configuration in general mixed with some posts about their own products.
Other vendors’ blogs:
e-Con Solution’s Blog – e-Con Solutions has a well written blog which usually explains things a little further compared to the competitors. Mixed into the feed are also some news about the company.
Apttus blog – Apttus blog is usually very focused on their products and releases, but mixed in is some very interesting content.