I have a theory on this one:
Apple has been deliberately fueling skeptical press coverage of the headset to lower expectations so that what Apple does unveil, which I believe will be a step better than what people have been anticipating, will wow people in a good way. If expectations are sky high, it's nearly impossible for any company to deliver something that delivers at that high of a bar. Lower them and then give something good, you exceed.
Now my second theory is that the $3,000 price is inaccurate and has been floating out there and repeated every day because Apple can generate more buzz and excitement by coming in lower, even if it's a tiny bit lower. $2,499 would sound like a good deal, right? Even $2,799 just reads better than $2,999/$3,000.
So ... the product will exceed what's on the market, advance the headset category by several steps and undercut price expectations. Toss that all together and you have (maybe) a winning product for now.