The fee is 4% and the max buy is $2,500 which means the max fee is $100 for the biggest purchase. I spent $10 and the fee was 4% ($0.40) which is not that bad considering many exchange withdrawal fees will charge you more than this (the average withdraw fee is 0.001 - 0.0005 bitcoin which is a few dollars) and when you login to the online account it lets you choose your fee when withdrawing. So I withdrew paying less than $0.01 with a 1 satoshi-per-byte fee (: I'm very satisfied with the whole experience!