Dear (Name of the person),
I want to let you know that our firm ABC has evaluated the proposal which was submitted by your firm XYZ. After careful consideration, we regret to inform you that the proposal was not selected because the amount you proposed of the products is really high that is why we cannot proceed further with that. The full proposal was just fine but you were beaten on price. In this epidemic situation, nobody will be ready to pay such a high price. The majority of people will be willing to pay less in return for good quality. You should be careful about your prices in your future proposals.
With the prices, you will be able to compete in the market. If you want to run your business for a long time and want to earn profits then you have to be careful with the consumer’s demand. I hope you understand what I am trying to say and will make changes in your proposal so that it will get selected next time.
I very well know how much time you have spent in making this proposal. Rejection is never a failure but it shows that you are one step closer to success. You should spend little time understanding the market mechanism and its behavior then I am pretty sure that the proposal which you make after knowing about the market will be the best and also it will get selected by many good firms.
I hope I will see your proposal in the coming future.