I have a very small Boston Terrier (only 7 pounds) and I had a hard time finding a carrier that was long enough AND tall enough for him, so I made my own using the instructions I found here: http://www.ehow.com/how_4911341_make-dog-carrier-purses.html
If you're at least a little sewing-savvy, the instructions are clear and well thought out, and the results are great!