I have two tops that are non-maternity but worked for me when I was pregnant. I'm normally an xs.
The first is a Free People spaghetti strap flowy top that worked before I got huge! XS - $10

The second is by Material Girl from Macy's. It's a grey cap sleeve hi-low type shirt that is really cute with leggings, it's s medium and worked almost til the end! - $8

S&h $3