most of the stuff for your birth kit is pretty easy to get. though some midwives will have you provide things that others don't. some things you will absolutely need: sheets you don't mind getting ruined, a plastic covering for the bed (this can be a shower curtain, a mattress protector), towels, receiving blankets, baby hats, a thermometer, pads for you, underpads (the large, flat absorbent pads that can usually be found with the depends), diapers, a heating pad or hot water bottle, it's a good idea to have ice packs or make frozen pads, a light source (to check for tearing and do any required stitches), garbage bags, hydrogen peroxide (for cleaning any blood). my midwife had me have a large bowl for catching the placenta, and I had a couple of dish tubs for puking into (not everyone does, but I puke during labor).
you may also want on hand: herbs, Tylenol, ibuprofen, a peri bottle (amazing for peeing postpartum, especially if you tear), and lanolin for sore nipples.
you will also want food in the house, you need to eat a lot postpartum, and depending on how long your labor is, those in attendance may need to eat, as might you.
and you'll want a way of warming your bedroom pretty quickly, you get really hot during labor, but really cold right after.
and I loved having bendy straws to drink from.