It might not be the best way to do it but you can use a lot of if sentences like this
if(isNull(Column1), 'Missing Data in col 1',
if(Incorrect Price Column2, 'Incorrect Price in col 2' ,
if(isNull(Column1) and Incorrect Price Column2, 'Missing Data in col 1, Incorrect Price in col 2'
)))
You just need to be caferul about how you use it because in this example it is never goin to be in the third condition because the first one was already fulfilled.