This fits right in line with my prediction [1] that we're all overestimating the amount of gold in the enclosure and that it's going to be cheaper than the high estimates. I'm still thinking $2,499 max. Can't wait to see what comes out on Monday.
Keep in mind doing this type of compositing usually makes the gold MORE expensive. Granted Apple could take it to an unprecedented scale but I couldn't wouldn't hang my hat on it just yet.
The people making much higher estimates of the gold watch's price (most notably, John Gruber) are backing their estimates with analysis and citations.