I know that sometimes it's too hard to find something to do or to buy on your anniversary …well that's okay … the most important thing is to be creative … it doesn't have to be fancy ... or expensive … I know a friend of mine … who took her BF out for a picnic that she made herself. She took him to the place they shared their first kiss, while they were eating, a CD she made of their songs was playing, she also gave him a picture of them in a frame she made, It was so fun, he loved it, and it was inexpensive.
Also you can book a table in a romantic restaurant, or a restaurant that have special memories for both of you, write a romantic letter or a poem, put it in an envelop with the restaurant reservation, hide it in a way that makes your BF see it in the mourning and join you in the dinner by the end of the day, this is also a romantic inexpensive way to celebrate your anniversary, or you can choose one of his fantasies and try to make it come true that night also you can arrange with the restaurant to serve your small gift with the dinner, or whatever … just be yourself and also be creative.
If he has a favorite radio channel you can call the station for a gift song with a note that says I love you, or if he has a pet you can wrap a small gift around his/her neck and make sure that your BF will find it when he come home.
There are more and more ideas, like thousand of them, you can use candles, find out his favorite sport and give him a related gift, you can make a nice small cake just for the two of you, one time I made a funny survey for my BF and all the questions were like … what is the percentage of your love to me? 20% , 50% , 80 % ,100 % , it was fun and he answered all the questions and send the answers to my home, we had fun that year, what I am just saying is be simple, be yourself and above all, be creative.