WTB 700c wheel with 9spd 12-25 cassette for trainer wheel

I'm looking for a spare rear wheel that I can swap out for use when I put my bike on the trainer. I've got one of those indoor trainer tires to put on it so I won't need a tire. I just need the wheel and cassette. Since it is only for use on the trainer high quality isn't an issue. Cheap is good.

Oh, and for the record... it will go onto a Bianchi Giro with 105 group so anything Shimano should be fine. Also, I'm a bike noob so any advice would be very welcome.