You make purchases from Amazon USA itself. Just use a freight forwarder (parcel forwarding service). Such companies provide you a virtual USA address, so you will be able to use it to make purchase on Amazon and other USA online stores. Some freight forwarders allow you to consolidate your packages, so you can save on delivery a lot.

See also:
- Major freight forwarders for shipping packages/parcels from Amazon & other US stores
- Online shops shipping and not shipping to Shipito warehouse in Torrance, CA