Grant,
How much of a drive is the collection from where you live in Washington? If it's a days drive, I'd just drive and bring it back. Is any of it graded? If it's all raw, then it just looks like cardboard sports cards. If it's slabbed stuff, then it looks like potential $$$ signs.
If it's a lot of cards that can't be hand carried then do you really want to put the cards in the cargo hold of a plane and have the cards potentially lost/damaged? I guess all the high $$ ticket items would be in the carry-on.
Edited to add - 10 years ago most people wouldn't have thought about declaring cardboard... Never really thought about the implications of moving the stuff across international borders. I can remember having (6) N162s (including an Anson) shipped to me from Australia. I never thought about the custom's/duties on that stuff. I just looked at it as baseball cards heading to my collection.