Moomin, yes how the Dassault bids play out in Brazil and UAE in particular, not so much India or Oman as I don't think they're seen as potential customers for F-35 yet - and it's current and potential customers that are likely to affect the price we eventually pay.
As for the no stated unit price thing, I doubt any of the three could offer any kind of price guarantee in this instance for a number of reasons; model, support contracts and numbers being the first that spring to my mind, so I wouldn't read too much into that just now.
I was going to say think of it like walking into a car salesroom, but realised that would be completely wrong. With the car, you can usually end up paying less than the first quoted price. With the aircraft, you can pretty much guarantee the cost will only go up - no matter which manufacturer you're talking to.