I saw a miniature Australian Shepherd the other day. Precious. The miniatures range between 17 and 35 lbs. Compare that to a full-size Aussie, like my Sammy, who is 50 lbs. If the miniature is still too big for you, yes you can get a toy Aussie!
With the option of a toy or mini Aussie, I'm not sure why anyone would ever get a small dog of another breed. No offense to any small dog owners out there. I'm just obsessed with the fluffiness (not to mention smarts) of the Aussie. Look how cute!