This is mostly a clarification. When crafting a masterwork item, are you comparing your progress by day to the base item price, or the price of a masterwork item?
An example. Let's say you have Craft (Weapons) +10 (for a nice even number) and you're crafting, all on your lonesome, a pair of longswords, one of them masterwork.
For the base longsword, it's normal complexity, DC 15 for 2gp/day. But since you hit DC 20, it's doubled, for 4gp/day. So it takes you a little less than four days to make a longsword.
The masterwork longsword is complex, DC 20 for 4gp/day. You can hit DC 20, so you're fine, but you don't have the +5 here, so it's just plain old 4gp/day. Now, the question... does it take just under four days to make the masterwork longsword, as above, or does it take 78.75 days to reach 315gp instead?
By way of comparison, under the core system, it would take 3.5 days to create the regular longsword, and 56 days to complete the masterwork version.
Bump?
Once again, bump?
RAW, it looks like the longer time.
This is probably more appropriate in the "Rules Questions" forum.
I have to say that I agree with Urath DM. the longer time would be required which would suck for us mundane crafters.