DHL and FedEX will typically result in a custom tax/duty import bill 2-4 weeks after delivery. This isn't DHL or FedEX being an ass, this is them doing business and paying the proper fee's. This typically results in any package sent into the US or Canada over $250. Some people say $200, $500, etc, however my experience has been $250 seems to be the magic number.
China Post is the only way to receive items typically without duty, however most sellers only use China Post for lower value items because of the shipping time also involved (weeks at times) most people do not want to use China Post are are okay paying a small additional duty bill.
Bottom line - Not to sound like an ass... If you want to use Aliexpress just understand what your doing which means import/export fee's need to be paid. Getting butt hurt and calling DHL or FedEx ass holes for doing there job makes you look like the idiot. Also, consider all this when making your purchase - thinking your saving $20 in the end could result in the same price had you purchased state side from a US business/seller...