Well, I have some (not a lot) of disposable income, and I would be asking the same questions if I found out I was expecting again, much less twins! I have a friend that just went through a very similar situation and so I will answer based upon what she has shared with me. Her first two were 24 months and 12 months when her twins were born. She figured out really fast to never say no or turn away from help or assistance despite her intense pride. I told her one day that any help she accepted now would be more than made up for when her children grew up and became caring, productive members of society. Not to mention the joy they bring to all of us right now! It's so much fun hanging out her house with the little ones! They are truely a gift.
Financially, other than learning to never say no to help or assistance, it was a real epiphany for her when she realized she doesn't need all the baby gear marketed to us western moms. They didn't need a closet full of outfits that would be worn only once, and she found out that gently worn outfits from garage sales were a god send. After the 2nd baby was born, her whole dogma changed. She shifted into "Mom" mode, centering her life around the babies. She didn't think about what she was missing out on or care that she didn't fashionable clothing. "This is my new normal" she said to people who asked how she did it. Expense wise, she saved money in areas she never anticipated. As it's really hard to take 4 toddlers anywhere, she never drove saving a ton in gas, mainenance, tires, etc. She's not even going to dream of new carpet or furniture until the kids are older. As she's at home all the time, she barely spends anything on clothing, makeup, or her hair - and she still looks neat and presentable. Her biggest expense has been diapers, as she got her formula through WIC. And her mom and aunt stockpiled diapers while she was pregnant with the twins so that wasn't too bad either. She grows a lot of their food, preserves it, and buys almost no processed foods.
We still laugh, though, thinking ahead 10 years to when she will have 4 teenage boys to feed. But she'll be able to get a parttime job by then to finance the food bill!