FYI, the replacement rubber inserts can be bought at any auto parts store (sorry, I don't have a part #). The whole blade assembly, however, is Toyota OEM only because of the plastic nub that aligns the blade assembly with the mounting tab when not in use. You can only buy it at the dealer or online. FWIW, I think it costs $5-$10.
I tried replacing just the rubber insert, but it didn't do much good, I still got a lot of streaking. Replacing the whole wiper assembly fixed the problem though. I use my wiper a lot, esp. in the winter. The spoiler doesn't seem to do $hit...
K.C.: Out of curiosity, which spoiler do you have? hump-back or non-hump back?