Soft but affordable sheets--what thread count?

We need to get new sheets for our queen size bed, but we don't have a ton of money to spend. What's the lowest thread count you can get and still have soft sheets? I made the mistake of buying cheaper sheets from Target, and they felt like sandpaper. Is 400 still pretty soft? We got a nice set of 440 thread count sheets for Christmas. Unfortunately, there are two small rips at the top, which I didn't notice until after I washed them. And where are the best places to get quality sheets for lower prices? Thanks!