How do costs of upgrades work with quality modifies?

For example does a Good Quality Mono-Sword cost

(3x10)+40= 70 thrones

or

3x(10+40)= 150 thrones

?

I feel it should be the first since you can get the good quality weapon then add the enhancement, but it could be that adding the upgrade to good quality weapons costs more.

The first one, you're not paying for a Good Quality Mono Upgrade after all.

First one, which makes the Assassin based on melee able to buy (if available) to buy a Best Qualtiy Mono Punch Dagger for 90 Thrones.