OMG, I'd almost cry of joy. One of the reason I don't use my faithful Apple //c is that it's so cumbersome to swap these floppies... but this is wonderful.
Wow, my dad bought an Apple //c when I was around 4 y.o. and it was kept at home until I was ~8, but I couldn't remember seeing a cassette port. At least I'm at peace now.
Gah, you're right. Unfortunately alternative storage adapters are really hard to find (do they only exist?) for the //c.