Buying a Portable Washer and Dryer?

I am researching portable washers and dryers that can be hooked up to my kitchen sink. I live on the 2nd floor of a duplex and my apartment does not have a laundry hookup.

The reviews vary from brand to brand and so far there is no clear ones to avoid or buy. I'm feeling a bit overwhelmed. The prices are more than buying a regular washer and dryer so I want to make sure I get the most bang for the buck.

Anyone have a portable unit and what brands I should look for or forget?

Thanks,
Melissa