$1911

Where does people get their big embroidery floss bobbin? I can't get it in my local craft store.

I buy most of my yarn online, including DMC petra which is the same size as embroidery floss but much cheaper.

?but much cheaper? but is it good floss? i mean, is the quality the same?

I think so. I only use it for kumihimos, so I don't know if it's as strong as embroidery floss but I think it is. The only difference is that you can't divide it in 6 smaller threads. It looks the same as DMC Cotton Pearle.
I paid a little less than 7 euro for a 100 grams (400 meter) cone, while embroidery floss is about 1,30 euro per skein (8 meter) here.

you could also buy embroidery floss from eBay. I buy it from there and it is really comfortable because it is cheaper and you can find a lot of skeins with very little money. :)