I am head of Purchase Deptt.in a private company.We had an agreement through E-mail with a company for the purchase of certain material at $500/ton.about 2-3 months ago.

In the name of Allah, Most Gracious, Most Merciful

Assalaamu `alaykum waRahmatullahi Wabarakatuh  

There could be two possible situations:
1) a mere promise was made to purchase the items.
2) The deal has already been concluded.

According to our understanding of your query, the supply company and you had agreed 2-3 months ago that goods will be supplied by the company to you at a certain price and the goods have not been purchased as yet. Now you wish to cancel this agreement because the material can be obtained cheaper elsewhere.

This is a promise which is only morally binding. You may inform the company that you wish to cancel this agreement. Thereafter you may purchase the material from an alternate supplier. 

If the deal has already been concluded with the first supplier via email or otherwise, it will be binding on you to purchase the goods even though it may be expensive. However, if the company agrees to refund you then this is their mere kindness towards you.

And Allah Ta'ala Knows Best

Checked and Approved by:

Mufti Ebrahim Desai
Darul Iftaa