I think the dealer is the best bet for the tranny filter/strainer. I haven't found one at the local part stores.
One dealer told me that the strainer is not replaceable unless you are rebuilding the tranny, so I walked out without arguing further.
You need P/N 25420-PY4-000 (strainer, #1 in pic) and 91308-PA9-003 (O-Ring, #21 in pic).