Section 9. Definition and Ascertainment of Price.—

1. The price may be fixed by the contract, or may be left to be fixed in such manner as may be agreed, or it may be determined by the course of dealing between the parties.

2. The price may be made payable in any personal property.

3. Where transferring or promising to transfer any interest in real estate constitutes the whole or part of the consideration for transferring or for promising to transfer the property in goods, this act shall not apply.

4. Where the price is not determined in accordance with the foregoing provisions the buyer must pay a reasonable price. What is a reasonable price is a question of fact dependent on the circumstances of each particular case.