I think you should get him something, and get him something for the anniversary, not the birthday, as it's not the same thing. He got you something for your anniversary to show you (I'm assuming) how happy he has been to be your husband for the 25 years, and to give you something to look at to remind you of that. Since he has made that gesture, you should do the same. Giving him something for his birthday is not the same at all.
It doesn't have to be anything as expensive as what he gave you, and I don't even think you have to give it to him soon (i.e. don't rush to buy just anything so you can give it to him now). Find something, or maybe even make something, like a collage of photos from your 25 years together - you can use shutterfly, etc. to do that for you if you can scan the photos into digital form. And then surprise him on a random day with his favorite meal or activity, and the gift.
From what I can tell, you have a wonderful husband. Consider yourself blessed, and let him know it : )