be for sale —(also: be up for sale) said of a house, car, etc. that an owner wants to sell:
- I wonder how he heard the house was for sale.
be on sale—
1. be available for buying in shops, etc.:
- Local delicacies, such as cheeses and wines, are on sale here at a very reasonable price.
2. be sold for a special low price:
- Tomato soup that is usually sold for sixty cents a can is now on sale for fifty cents.