Let me clear something up with regards to how nvidia determines their pricing:
Unless nvidia doesn't care about profit maximization or is supply constrained, they cannot simply price cards however they want. They can't price is sky high if their primary consideration is maximum profit. I see folks here suggesting that "oh AMD doesn't have HD9000 yet, that means nvidia can do whatever they want with the price". Hmm, that's a tricky proposition. Generally, no you can't - generally speaking, nvidia doesn't do this. They price to maximize profit, and sky high prices doesn't accomplish that (explanation below) but in certain market/supply conditions firms will price above market. They can price over market price in two situations:
1) supply constraint (this is plausible since GK110 is also being used for HPC)
2) they don't care about profit maximization.
What really happens is firms will study price versus buyer base very very extensively - and based on this, they can formulate a price that is the best compromise between getting the most buyers and getting a reasonable amount of profit. Believe it or not, you get higher profits by pricing things at what consumers expect, at the typical pricing level. You absolutely do not maximize profit by pricing things sky high out of cockiness. (GK110 is a bit different in this respect, i'll discuss it below) This is because for every X dollars you raise the price of the product, Y consumers will exit the market.
This is very easy to understand. There are consumers who have set price limits independent of their income - these are people with mortgages, priorities, etc. Now some will pay anything, I would say these are the less intelligent folk who purchase out of passion. Most consumers have a strict price line and will not pass it. For instance, many bought the GTX 670 at 400$ But they would not have bought it at 550$. Absolutely not. As an another example, look no further than intel - notice how their i7 quad cores are usually always priced around 325-350$? And the i5 x570 parts are around 200$? Now, when's the last time intel had serious competition with high end CPUs? You'll notice they don't increase their i7 quad prices to 600$ out of arrogance, they price it to maximize profit. Again...for every X amount of dollars you raise the price, Y consumers leave the market.
Consumers aren't sheep that pay anything you tell them, in this day and age they're informed,have expectations in regards to price, and they have price limits.
Profit maximization is a pretty basic concept studied early in economics. You can't, even if a competitor does not have a competing part, price something ridiculously high and get the most profit via this method.
Now, with the GK110 - they actually can price it a bit higher because these chips are also used for HPC and Quadro cards. They want to reserve a certain amount of chips for that, a higher profit segment. But let's discuss the 770 for a moment. I've seen some here state that nvidia can price it however they want because AMD doesn't have a competing part. It doesn't matter whether a competing part exists, profit maximization still dictates the price. 550$ excludes a lot of the market who have strict price limits and priorities. In fact, whoever said the GTX 770 would be 550$, that is laughable. Period. (This is based on the assumption that 770 will be 2GB, BTW) I'm about 99% sure the 770 will be 400$ and not a penny more - we'll see on the 23rd

Now the 780 being the GK110, nvidia has more flexibility here - they may not want to make this a volume part, and they may not want to maximize profit with GK110 as a Geforce. As a Quadro, perhaps... As mentioned earlier, they can also use these chips in Quadro cards which are a higher profit segment. Even with that in consideration, the 780 absolutely will not be 800$. I can guarantee that. That will exclude so much of the market that they will make less money overall - I expect it to be around 600$, which is a reasonable cost for 3GB. 650$,
MAYBE, that is really really pushing it. Again, we'll see on the 23rd.