My youngest is 3 weeks old today and honestly I had the same thoughts. I bought small books, stickers, a small sticker book, and a few other little things for my two older boys (4 and 2 1/2 years old) but now I am saving them for their Easter baskets. EVERYONE brought them something to the point where my 4 year old almost expects something when someone walks through the door. They are both pretty happy about the baby, but I was shocked by how many things people brought them. (Grateful, but surprised--although I usually bring something for older siblings with a new baby, too.)
So, I would keep it small and talk up a date you'll have with her when the baby is old enough for Daddy to give him/her a bottle. My husband gets to start the first one anytime after today and my oldest is very excited that he's going to go "out" with mommy alone (we'll probably get fries and a smoothie at McDonald's, but he doesn't care). Good luck with the rest of your pregnancy!