S.B.
I had a great baby shower for my first child and being in a really tight financial position all of the gifts really helped me prepare. Just the same I don't plan on having one for my second. I have to admit that I side with having one shower no matter how matter children you have. More specifically I feel that a full blown shower with lots of gifts and registry is only for the first. I do, however, believe that all newborns should be be celebrated and that the event should be shared with friends and family. Personally, I'd go with a smaller event after the baby is born to welcome her home and, as others have already recommended, tell those who ask what you could really use.
I would happily give a welcoming but as someone on a really tight budget I would feel uncomfortable having to buy gifts for a friends second or third shower as well. Then again I could always decline the invitation.
Congratulations and best of luck!!