I agree that when you can't afford a lot of those babies things.. you just learn to live without them. Most of those things are really not necessary.
Sonogram- I would skip it, even with the family history
Crib and mattress you have - sell it and cosleep instead
crib sheets - don't need them if you cosleep
food processor - definitely not needed. just feed the baby bites of your food when they are old enough For some of the things you need:
-diapers (I use receiving blankets as flats. I somehow ended up with like 10 from the hospital, or you can buy them for often less than a dollar secondhand. Then you just need some cheap covers, like LiteWraps $8 each and some pins)
You could probably get away with diapering your baby with this system, from birth to potty training for under $100 - and you wouldn't need to buy all that at once.
-scraps of fabric to make into washcloths for wipes (just run/stitch a seam around the edge of square scraps)
I also agree that you CAN do this!