Cancelling buildings/Extractor-Trick

I've become aware that cancelling buildings now costs minerals.
Any1 knows the reference point on how much this actually is?

2nd Q: Normally playing 12 overlord, pool - nevertheless advisable?

Thx in adv!

 

There is a thread somewhere that deals with 10/10 11/10 and 12/10, and 11/10 comes out slightly ahead. As for how much it costs, since you should cancel the building immediately then it's safe to say that it costs 1 mineral. I don't know how cost increases the longer you keep the mutation.

 

I believe it's a quarter of the price of the building. Of course terrans can salvage even buildings which are completely done and get back 100% of the cost.

 

I thought only bunkers could be salvaged

 

Oh yeah, I think that's true. Confused that a bit in my "terran's op mood"

 

So the mineral loss is for every structure or only Extractor/Assi/Raff, and it is a fix amount?
@kuvasz: You remember the thread(name)?
thx