Yes, after decades of home media releases no one should take these MSRP's seriously and at most retailers that will never be the final price.
Given recent pricing trends, I'm not sure if street date will be as low as $25-30, but it certainly won't be $49.
Nolan's deal with Universal for the film reportedly included a 100-day theatrical window, so I don't think they could release it too much earlier than they are. Released July 21, today wouldn't yet be 90 days.