My husband and I were in between moving after our son was born last January. We had gotten a travel bassinet (a tall one) which we used until he got too big. We then did get a pack and play since we were moving down here and did not yet have a house. He kinda slept in that until about 3 months ago when we finally got his crib. I don't know if it really makes a difference, but he does sleep a lot better in his crib, but that could be just because he was older. My suggestion is to just go with the crib. Pick up the crib itself maybe this month and then get the mattress right before she was born. I know it's hard when things are tight, having very much experience in that department, but if you invest the couple hundred dollars in the crib it will be something your child will use for years. I believe that my son sleeps better in a crib vs the playpen.
I was also going to say that we bought our son's infant car seat in jan of 05, so it just about a year old. It is still in great shape, but it is blue. I know that I was very hesitant to use a used car seat, but it has not been abused and it is just under a year old, so if that is something you wouldn't mind using, even though it is blue, you are more then welcome to have it. I was going to give it to a girl due in a few days up north, but she got one for her baby shower. If you are hesitant I understand, but wanted to offer before I gave it somewhere else.
Hope this helps.