Obviously, the ideal Rolex steel-sports purchase is at a duty-free Rolex AD -- at the airport for example. But legally you should be declaring the purchase as you go through customs in your country anyway. (And the odds that the watch is available as you make your way through the airport are slim.)
So realistically, you buy at a local AD where you'll pay full price plus sales tax. In many big cities like Chicago, New York, or Los Angeles, you'll pay close to 10% in sales tax. In many countries in Europe, we're talking 20%. On a Hulk, Daytona, or Pepsi this is big money.
There is no telling when the watch will be available at your AD, and what the sales tax or MSRP will be at when the watch is available, as waiting lists are not made public. The only thing you know is that there will be no discount. With time, MSRP and sales tax are likely to go up, not down. Sales taxes are less unpopular than property taxes because it is a consumer tax. Americans are often cash-poor but land-rich. So sales taxes are more likely to be approved or voted on to bolster state coffers. Rolex MSRP can only go up, as I believe Rolex steel-sports models are currently underpriced; I believe the new movements will be the justification for the price increase.
Online grey dealers are not currently under the obligation to charge sales tax. This might soon change as Internet sales taxes are falling under more scrutiny because brick-and-mortars complain they can't compete. I predict online sellers in all industries will be made responsible for charging sales tax at checkout. Currently online grey dealers will offer no sales tax and free overnight shipping. (I'm not a grey dealer, just a Rolex lover.)
If Rolex shortage is mostly due to increased demand, and more people than ever in the history of the world have the financial wherewithal to buy into such an aspirational brand -- whose reputation constantly ranks first -- the shortage might get worse, not better. I heard Rolex is increasing output, but I don't think we've seen the peak demand yet -- and demand will continue to outpace supply.
Do you want to wait one or two more years for that hard-to-get Rolex and roll the dice to save $500, $1000 or even $2000 depending on the model? MSRP and sales tax are both such unknown variables that paying "grey prices" now can make sense. Plus, in two years, who knows what the market value will be. The Daytona didn't jump straight from $12,000 to $22,000. But it has relentlessly gone up and is standing at $22,000 now.
So go buy that Hulk or BLNR and enjoy them now!