While grandma can be easy to buy for, she can also be very difficult. The challenge is to find a gift that she has not received in her 60-plus years on this earth. While you may not be able to accomplish that by buying a material gift, you can do it by being creative.
First things first, grandmas like to bake. They especially like baking for their grandkids, so get her a gift that will benefit the both of you. Perhaps spend the money and buy her a special new baking appliance that will allow her to have the joys of baking, and allow you to enjoy the fruits of her labor.
Of course, not all gifts should put your grandma to work and have an ulterior motive. For your grandmother, the most important thing she has is the memories, so try and find her a gift that celebrates that. Put together a quilt with her grandchildren's names on it, or make a collage of her and the grandkids together throughout their lives.
If you have the money, one of the best gifts you can possibly by for both your grandmother and grandfather is the gift of a life experience. Throughout their lives, they have accumulated a lot but if they have not touched the Pyramids and have always wanted to, something in their lives will be lacking. Give them the gift of a life experience and memory that will live with them for the rest of their lives. Beyond a material gift, beyond a sentimental gift, this is the gift that will mean the most to them.
As stated before, Grandmothers are easy enough to buy for if you know what to look for. Sentimental is good, so is anything that highlights their hobbies, whether it be quilting, sewing or baking. If your grandmother is a fan of Thrash Metal, (and it could happen), then play into that and get the gift that will make her the happiest.
Remember, one of the greatest gifts your grandmother has is you, so maybe a coupon for a weekend with her every two weeks would be the perfect gift of them all. It is something to think about when you are trying to find the perfect gift for her.