Suggested changes in purple:
Congratulations! This is YOUR LUCKY DAY because you are being given the opportunity to save a good sum of money on your tax bill while at the same time helping some people who are in very serious need of your help.
Each year (remove comma) Buckeye Bread Basket, a nonprofit organization that has served the community for many years, will have a Thanksgiving Day dinner for those less fortunate who can't afford a simple meal, much less the traditional turkey feast. More than 400 needy people, both single people and families, are expected to attend this dinner.
However, today's tough economic conditions make it difficult for Buckeye Bread Basket to meet those needs without help from people like you. We will have our holiday fundraising sale to raise the necessary funds. We are planning to sell holiday greeting cards, which come in boxes of ten with green envelopes, and which feature an original watercolor scene created by a famous Ohio artist.
We would like to ask your help in raising money for this very worthy cause by simply buying our holiday greeting cards. For the price of $24.50, the money from the sale of a single box can feed a hungry family of four on Thanksgiving. Please place your orders by using the enclosed form and return envelope.
We thank you for your generous support, and wish you and your family the very best of the holiday season.
By the way, most of my changes were not because of your English or grammar; they are simply because I've had some experience in fundraising so I changed a little bit of your phrasing. The changes are just suggestions, of course. Good luck with your campaign!