I disagree that selling to professors is a bad idea. Personally, I suspect it is the only way to enter the market. Now I doubt that if a University approches you and asks to buy your product that you'd turn them down, but that will not happen until you've proven you have a much better product. You will never convince a whole University to switch to your new product unless it, works exactly the same in every-way, better in every way, and migrates in 10 minutes. There will be people who know Blackboard and oppose it because they don't want to have to learn a new system. Furthermore, it is unlikely you will convince a University to buy both Blackboard and your product.

The only people you could convince to buy your product are individual professors (or small departments) who hate Blackboard, which according to a quick survey is near 100%. Now many perhaps most are not willing to spend money for a class but there is a sizable percentage of professors that do care about teaching and would be willing to spend their own time/money to improve their students education. Even if a professor is acting selfishly Blackboard is such a pile of crap I see some professors paying money to not have to interact with it on a daily basis.

(On a side note my classmates wrote a program called Ben in High School back in the early 2000's that was used by the whole school, it was better than Blackboard. So I have a special personal hatred of the towards it.)