Important event coming up in my family. I would ...

I don't believe in extravagant expenses as a way to express your love. Simplicity is the best. I would send a bouquet of flowers and attach a card you can make yourself. You can find some pictures in magazines, to paste on the card, and you can buy nice interesting paper to write on. I would also look for an interesting poem that would capture the way you feel. Hope this helps you. Have a great event.   

A bond with your mother sounds like something special. Go for the intimate. I agree that no great gestures are required, rather being kind and thoughtful and showing you care.

Cooking, buying one small thing she's always wanted, sending her a token of love - all I am sure - will be greatly appreciated.

I heard of a family that sent their mother abroad for a 2 weeks vacation, but make sure you can afford it and that she would enjoy it, because it is not for everyone. 

Try making an album with great memories you have of her, combine pictures with your own personal words to express you feelings toward her.

Make a video presentation with pictures, home movies, special quotes, thoughts and well wishes for that special woman who has sacrificed so much for your own happiness.  Let her know through this presentation that her selflessness is not overlooked and that your love for her is infinite.

Hope this helps, Best Wishes!