I also really like the Green Devil BB's. Haven't used them for 3 years but they were pretty decent back then. If they haven't changed anything they'll still be decent and if they have improved them they'll be even better. They're quite popular in Europe/UK, I remember paying a little less than 15 quid for a bag of 4K BB's IIRC.
That said use what's available and if you "truly" want them to be bio look for independent lab testing to verify (IIRC Bioval and Green Devil have this because they're Bios are approved for use in the EU, madbull probably does as well).
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE