Simply replace the unfilled areas such as "" and "[date]" with your information.
Due to the increase in raw material costs, we must raise the cost of our products to you.
We have avoided raising our prices for as long as possible, but we can no longer prolong it.
We have enclosed our new price list for your review which goes into effect on [date]. Any orders placed between now and [date of increase] will be honored at the lower prices.
We wish to thank you for your valued account and know that you will understand the reasons for this measure.