If you're in the North East The War Store in NY is supposedly the big store that sells more high end guns http://www.thewarstore.org/airsoft
If you want high end then PTW's are only a cool $1500 USD. We would probably pay $2000-2200 for the same thing.
If that's a bit too rich for your blood then they also sell Classic Army (proline) and VFC stuff too.
Otherwise your best bet is to order from Asia from a place like Redwolf, Den, WGC, War4, eHobby, GunsnGuys, etc. Since you can. Just make sure you request the retailer cover up trades with black tape, or putty and also put an orange flash hider on the tip and it will clear US customs. We on the other hand can't because if it's fun it's most likely banned by the gummint.