In general, the more natural your birth is and the shorter you're in the hospital, the less your birth costs.
I'll be having a homebirth with a midwife and all but around $600 will be covered by insurance.
You can bring your own tissues, bottled water, socks, etc... to the hospital, but don't bring any of your own meds. That's a no-no unless it's something unusual that the hospital doesn't stock. Then, you will still need your doctor to write an order that it is ok for you to take.