Replying To [RookieTrader]:
Usually a LOI is issued for items like coal, iron ore and other large quantity items. It is purely a letter stating that you are interested and intend to purchase XYZ etc.
I would suggest you can always get one addressed to YOU from the Buyer, and then YOU issue one on your letterhead to the seller. After all, The Seller sells to you (therefore you become the buyer), then you sell to the end Buyer, thus you becoming the seller and he becomes the buyer. Two seperate transactions.
Once the deal goes down, the Buyer issues a transferable LC to you, and you transfer it to the Seller, thus getting your commission in between.