We supplied the colorfabb filament used to make your printer and the green spool that came with it. printedsolid.com. I've been printing for a while and consider the colorfabb PLA/PHA material to be the best I've used, which is why I sell it in the US. Pricing is relatively high, but in line with other premium/specialty material (fabberdashery, diamond age, etc).
As far as good quality standard filament goes, I've been really happy with toybuilderlabs.com (prototype supply on amazon) and protoparadigm.
I'm not going to throw out names of suppliers to not buy from, but I can say for sure that any time I've bought a spool for under $30/kg I've regretted it. I've seen filament with issues ranging from simple out of tolerance sections that plugged the hot end to more serious issues like wood chips in the filament that required the barrel of the hot end to be drilled out and filament that had actually been glued to the side of the spool.