Do you need a pump if you stay at home with your baby and breastfeeding is going well ? My quick and dirty answer: no. Most moms will say that you need a pump if you want to go out occasionaly and have your mom, your mother-in-law or anyone else looking after your child for a few hours. Not owning a pump does NOT mean that you can not ever go out ! You can very well hand-express your milk. Hand expression is easy, efficient, and you do not risk to injure yourself with a pump that is working to hard or not well adjusted to your breasts. Moreover, just like breastfeeding, it is free.
I remember waking up during the night with very full breasts, leaking milk in bed. If for a special reason I did not want to wake up my daughter, I would go to the bathroom and hand express some milk, just to make sure I would not get engorged. I was not collecting the milk and did not need to pay a special attention to containers and ways to preserve the milk for a later use. If you plan on going out and having someone look after your baby while he is under six months and you are still exclusively breastfeeding, you’ll have to look into ways to collect and save your milk safely. But if you stay at home (I mean, not IN the home, but not working) and arrange for your activities to be baby-friendly (have you ever heard of Movies for Mommies ? Theater screenings specifically for parents, with changing tables, softer sound, etc.), the need to pump should not arise very often, if it arises at all.