LOI is a Legally Worthless Document That Means Virtually Nothing _ As a practical matter, in legal terms, the Letter of Intent is a worthless and meaningless document. The LOI is a badly flawed legal document. This is because the document is, as one experienced contract law expert put it, "an agreement to agree which is non_binding and non_enforceable as a contract."
If what you want is a quotation or offer, then sending a letter of intent makes you look ignorant while requesting a quotation will generally at least make you look like you know what it is that you want. And what you want, after all, is a price quote. Hence you want to request a price quote, via a request for quotation.