I am in the process of getting an import permit as well. Before I mailed in my application today I called the office to clarify some things. I asked if the genus nepenthes was covered under the permit form PPQ 597. I was told that yes they are, but they are on CITES so I was asked if they are for personal use or profit. This seems to be the key as I understand it. For personal collection / growing the general import permit (PPQ 597) covers CITES plants including nepenthes. However, if the CITES plants are for reselling (profit) then a $70 CITES permit is required (PPQ 621). Therefore I was told by the USDA office that PPQ 557 is all that is needed for the import of nepenthes for personal collection. The USDA website also states this (but not so matter of factly).