That's ridiculous to blame all this on Nvidia when it was AMD that shot the first bullet.
For the most part, AMD has made mid range sized parts and charged prices slightly above midrange for these parts. What started this rip off generation was AMD when they started to charge high end prices for midrange size parts.
AMD released the 7970 at $550 months before the gtx 680 launched at $499. The worst part of it was that AMD didn't particularly move the price to performance bar with this move. It's price to performance was the same as the gtx 580 which didn't provide good price to performance in the first place.
https://www.techpowerup.com/reviews/AMD/HD_7970/30.html
The gtx 680 provided a generous increase as far as price to performance goes over the 7970(less so over the gtx 580 as prices had fallen already).
The fact that a gtx 680 had better price to performance over a 7950 just showed how out of line AMD pricing was. It wasn't just tahiti that raised the pricing bar, it was pitcairns too.
The 7870 was priced at 350 dollars at launch. You have to remember the die size of pitcairns was 212mm2. That's more along the lines of low end die size and AMD was charging more than the gtx 970 pricing.
And this was all before keplar was launched. AMD horrible pricing is what lead to the collapse of their marketshare as most people stood on the fence to see what Nvidia had in store.
If AMD didn't decide to raise the pricing bar, all of Nvidia's line would have been cheaper. It's mostly because Nvidia that all of AMD lineup got price cuts and they became the value company again.
AMD value pricing at the moment is more of a reflection of the cards not selling and the market correcting the pricing than AMD generosity.
When the generally value brand starts raising prices, it give the market leader the ability to raise prices.
BTW, its partners that decide how much it costs for additional memory, not nvidia.