Dear (Name of the person),
We regret to inform you that after evaluating your proposal carefully we cannot accept it. I know that it is your new firm and you wanted it badly. I am so sorry for declining it due to a lack of availability of varieties of the product that is why we cannot proceed forward regarding the proposal. Other things of a proposal such as the description of the price, management summary, and important information related to products are perfect but we are planning to offer a high range of variety which is missing in your proposal. We want a proposal in which we can offer 99% of customer satisfaction which can be fulfilled only by the variety of the products.
I can understand that making a proposal is not an easy task and it takes a lot of study about market and consumer behavior. Nowadays customers are not only impressed with the lower prices but also want a high range of variety in different products. Customers always show interest to explore new things so you must try to make a proposal in which you can also add variety for the products. I hope you will take this rejection as a positive note and will try to make changes in your proposal so that it will be accepted in the future.
It is the beginning of your business and I hope that it will reach its heights and your proposal will be in high demand by the firms. Wish you luck and hope that our paths will cross in the future.