I need to hear a much stronger case for Digi-Key having monopoly pricing power than just an assertion. Aren't the distributors market shares fairly fragmented (the assumption I'm operating on)? Digi-Key seems to have a large market share because it has built some kind of service reputation.
I don't really understand the legal position of scraping (and I'd love to see an accessible semi-authoritative explanation of the current state), but I do read lots of TOS's that basically say that that information is _not_ "public domain".
I'm in spiritual agreement with you as to what benefits part buyers the most (I think most people are wise enough to factor in some level of service into cost), but I think it's useful to think about Digi-Key's motivations in more dimensions than just good/evil. Again, I offer the pricewatch feedback/stars as an initial step that might address at least one apparent grievance. Not that that would stop them from fighting you (and good luck on that).
That's a central question though. Digi-Key doesn't want to compete on price (potentially because they believe that the price reported isn't an accurate portrayal of their offering, because of inventory, service, et al). The problem with that is that it doesn't help (actively hinders?) the reduction information costs for the other market participants (Octopart's value as I understand it). Whether this is evil or not depends on what brand of free marketeer you are...
One possible way to address this would be to incorporate some kind of a service metric into Octopart, similar to the way that pricewatch evolved.