Since the least expensive 18K gold luxury watch usually starts well north of $10,000, Apple can say exactly the same at a $5000 price point.
Also while Gruber says $5,000 a likely starting point he also says "... I made a friendly bet last week with a few friends on the starting price for the Edition models, and I bet on
$9,999..."
While it could come in lower than 5G I just don't see anyway it will be $1,500. If going for this 'bottom' feeder market Apple would have just used the more common consumer grade jewelry of 14K. Using 18K gives a STRONG hint that Apple is looking more upscale.
Also to add another hint: Look at the band hardware (18K too). It is put together with 4 screws instead of rivet fasteners. The 2 rivet fasteners appear to hold a tension spring. Anyone in the jewelry business will tell you this is a sign of quality.
Image