There are at least two kind of portable washers, by the size. The small one is too small, and I am afraid it can only wash two skirts at once. the price is about 300. The other one is a bit larger, and I believe it's suitable for apartment users. However, the price is about 500 to 600 bucks, which is too high for me.

and finally, I am still do my laundry in the common laundry room.