I suspect with the recent turmoil in the stockmarket the old arbitrage of buying big name watches (Rolex, AP, PP etc) and immediately selling to grey market dealers for a small profit on the RRP no longer applies...
actually it hasn't been valid for quite a few months, you can sense that when more and more dealers are putting out rolex watches to sell instead of merely serving as a showroom. that said, i am sure the highly sought after ones like royal oak, nautilaus, will still be unavailable mostly.
i wouldn't call it an arbitrage just the process of trying to get allocation of a lowly supplied goods and hoping the demand is still high and drum up pricing bids.