Too often men feel that a woman wants something material to make her feel appreciated. While that may be true, more often than not the little things mean so much more. By little things, I mean paying attention to her needs; taking some of the burden off of her.
Your wife has been pregnant for a long time. I'm sure it seems much longer to her than it really has been. By the time she comes home from the hospital with the new baby, she will have endured a lot of pain and she will be exhausted. She will most likely appreciate being pampered in little ways. Put as much time as you can into taking care of the baby. That will have a double benefit as it will give you bonding time with your new child. Give her a chance to rest. Rub her feet, give her a massage.
In particular, pay attention to her mood when the visitors descend upon her and the baby. If you sense that she's starting to feel tired, shoo the visitors out. Sometimes the Grandmoms try to take over. If you see that happening, run interferance. Wait on her, attend to her needs, make her feel special. Remind her how beautiful she is because she won't be feeling beautiful right away.
These things mean so much more than buying something at the store. But you know your wife best. If you think something bought will make her feel good, do that, too.
And congatulations on the new addition. Best of luck to you all.