Children cost money, but they don't have to be expensive. It's all about how you want to live and what you are willing to sacrifice.

You don't need to buy all new clothes, hand me downs are fine.
You don't need to go out for dinner together once a week, every now and then picking up a pizza is fine.
You don't need brand new furniture, buy off ebay.

You get the point. I think if you want a big family, there are still ways to afford it. If you want a lavish life, you might not be able to do that with 4 kids unless you or DH have a very high income.

Me personally, I would put family before luxuries. Which is why we are moving to the 'burbs, by second hand furniture and clothes, eat cheap, live cheap.

HTH