Their margins are high. About 8 times what you would pay for quantity 1 of the component from a Chinese supplier. E.g. 1.8" TFT screen they sell for $29.95 is less than $4 shipped via AliExpress.
However, they do provide a value add in the form of dealing with the Chinese supplier and their knowledgebase. Of course you could buy the same board off of aliexpress and then hit up Adafruit for the documentation (or be a badass and go out on your own) but they provide both the ability to buy just one from a US supplier and decent docs in the same place. Sometimes I value convenience over raw costs.
