For some reason, I was willing to pay $100 per season of TNG when it was released on DVD. I am not sure I'd be willing to pay the same price now to upgrade to blu-ray, but I think the $70-80 range is acceptable given the amount of work and level of detail given to this release. We're not talking about just a new transfer from the original episode masters. They're literally re-editing the entire series, re-compositing all of the visual f/x, and in some cases, creating new f/x shots. That's simply a huge undertaking, and I am grateful that CBS/Paramount is giving TNG such an extensive treatment. I don't mind paying a little more than usual for something like this.
Of course, eventually, the price on these will drop dramatically. That always happens.