Hi,
I've nursed 3 kids and never had an electric pump. I'm also a SAHM and I used a manual Avent Isis when I needed to either pump a bottle (I never had much stored since I was almost ALWAYS with my kids), or relieve some engorgement. I found it worked great, was easy to use, and when I was full I could pump a full 7-8 ounces from one side with it (production was not an issue for me).
This is what I suggest - have your baby and nurse on demand. That means that you nurse whenever the baby cries for the first 6 weeks. This in itself takes time and energy (especially with 2 other kids to care for) so prepare yourself to spend time nursing. Have books and videos, coloring books, kid magazines, legos, whatever your older children like to do, available and ready for them so they can entertain themselves while you nurse every 2 hours :)
Around week 4, you should think about pumping a bottle. I waited longer and my kids were really reluctant to take one. I think if I'd started just a little earlier it would have gone better.. maybe not.. just a theory.
At that point, a manual (used - all the parts are dishwasher safe) Avent Isis should provide you with a bottle a day or more if you want. I could pump a bottle in about 10 minutes.
Good luck and CONGRATULATIONS!
Jessica