Maybe try the Asian airsoft stores.
WGC, Den Trinity, War4Toys, UNCompany, eHobby come to mind.
Are there any local airsoft stores that stock small parts or how does it work for you?
In the worst case Airsoftparts.ca will likely be able to get you what you need but then you're paying shipping from Asia to Canada then from Canada to Brazil so it's not very economical.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE