Greetings, Anil!
This might help you with costs. This chart shows the basic
edition for Blackboard over the last few years. I think that
might be what you are referring to as "K-12 Starter Edition".
http://moodle.org/mod/forum/discuss.php?d=44666#204964
In my experience, BB itself does not provide content. As a
university, we were able to get content (course cartridges) from major
publishers. The students bought the right to use the content with
an encryption key along with the text. The two times I used a
course cartridge, the publisher actually loaded it onto the
server. It is possible that there were some groups that shared
teacher-created content in the Blackboard users group. I never
participated there, but Blackboard does have a conference each year and
individuals present at a lot of instructional technology
conferences. You might be able to find a "swap" area.
FWIW, here is the cost chart that I developed. You are free to use it if you think it would be of any value.
http://moodle.org/mod/forum/discuss.php?d=42276&parent=202057
atw