Thanks so much for all the replies, everyone. Much appreciated. As mentioned above, I'm hitting a wall with the "known shipper" requirement, and I was hoping that there were some intermediary service that I could use that caters to individuals rather than businesses (or rather, caters to individuals as well as businesses). Delta made it clear that I can't just walk into the shipping office and drop off the boxes without first having arranged and paid for the shipment through a third party "freight forwarder", so I was hoping that perhaps someone was aware of a way to work within those rules.

I checked UPS/Fedex, and using retail rates the costs are all well over $1,000. UPS has a "hundredweight" program that is cheaper, but I'm running into a similar problem as that program relies on a pre-existing commercial relationship with UPS. You can't even determine the price without first having a UPS commercial agreement to determine which class you're in, but the highest price tier (which I assume is for low volume shippers) is still over $3.00 per pound so still much, much more expensive than USPS and airline cargo.

As someone else mentioned, USPS is about 97/box, or ~$680. Right now, that's looking to be the best we'll do. The airlines are all in the mid $400's but we can't seem to figure out how to ship with them. To one other point, we're not flying to Hawaii any time soon so we can't check these as additional baggage. These are for a friend who moved to Hawaii to find work and left her belongings behind; she found work and is staying, so we're sending everything over to her (mostly clothes/shoes/etc).

Kalitta air is interesting, but it also looks like it caters towards large volume commercial shippers. I'll keep looking into it.