I was a nursing mom, too!
My advice:
~If you find that electric pumps are too expensive, the best hand held (battery and electric free) pump I have ever used was the Avent Isis. I LOVED it...and recommend it to everyone. I could get just as much with it, and just as quickly, as with an electric pump.
They sell the Avent Isis alone, but they also have it in kits for working mothers-in a bag with a cooler compartment to hold the milk after pumping. It is really a nice setup.
For longer term storage-like freezing-I preferred the Lansinoh storage bags, the ones with the ziploc style closure. They were much more convenient than the ones with the ties.
The key to pumping while working, is getting a day's worth of supply, etc. in advance, before you go back to work. Then, while at work, you pump milk that will be used the next day (or day after) while the caregiver gives the milk that has already been stored. It's a nice system.
If you can't pump at work for some reason (and I would discuss this with your boss, because many are surprisingly lenient here-and you can do so on your breaks, etc.) then some women choose to have the caregiver feed formula during working hours, and then nursing resumes when the mother is home. After a few days of this, your body adjusts to the new feeding schedule. This is a nice option if necessary-because ANY breastfeeding is better than none, it doesn't have to be an "all or nothing" type of situation. Any milk you can provide to your child is better than none at all.
I am definitely a breastfeeding advocate-personally, I LOVED it. I wasn't able to nurse immediately after birth with my first (I had surgery after the birth) but I nursed my second and third IMMEDIATELY after delivery...when they were just minutes old. It can be hard, but at the same time, such a bonding experience like no other.
I am so excited-my SIL had her baby on October 30, and after discussing it with me through her pregnancy, and her having been around when I was having mine, she has decided to breastfeed as well. It just makes me gush to see it...
to all the nursing moms, and future nursing moms.