Just be careful. Technically, modafinil and it's newer cousin armodafinil are Schedule IV controlled substances in the USA (same as many of the benzos.)

I don't think there are (m)any cases of people being busted for importing/simple possession, but if you were to get arrested for something else and had it on you, I wouldn't be surprised if you get additional charges.

Point being, this isn't a legal supplement you're ordering through the US Postal Service.