Help with crafting process

[Invader]

OK, I'm trying to make sure I have the crafting process correct for the artificer I'm making and I've never really bothered with any kind of crafting before.

I'd like to craft a masterwork mithril chain shirt so here's how I understand it

I have Extraordinary Artisan so -25% gp off the bat.

Mithril shirt = 1,100 -25% = 825gp base price

825/3 (raw material cost) = 275 gp

275 x 10(sp) = 2,750

My craft check was 19 against a DC of 16 (10 plus AC bonus) = 304
(I continue this process every week until that total equals or exceeds 2,750 (cost in sp)

For the masterwork part it says "The masterwork component has it's own price (150gp for armor) and then it says Note* The amount you pay for the masterwork component is 1/3 the given amount just as the cost in raw materials.

So for armor its 150gp/3 = 50 x 10 (sp) = 500 for my craft checks
Gp. Cost would be 150 - 25% / 3 = 38gp.

So in the end for a masterwork mithril shirt I would be paying 275gp + 38gp. (150 -25%/3), for a total of 313gp and how ever many weeks it takes to make all my craft checks for both the armor and the masterwork component?

EDIT* And you're able to take 10 on crafting skills but you can't take 20, correct?

[Invader]

*Reformulated

For the masterwork part it says "The masterwork component has it's own price (150gp for armor) and then it says Note* The amount you pay for the masterwork component is 1/3 the given amount just as the cost in raw materials.

So for armor its 1,1100 + 150gp/3 = 417gp
And 150 x 10 (sp) = 1500 for my craft checks


So in the end for a masterwork mithril shirt I would be paying 417gp and how ever many weeks it takes to make all my craft checks for both the armor and the masterwork component?

EDIT* And you're able to take 10 on crafting skills but you can't take 20, correct?