Good luck with your adoption!!!
I second everyone with going to yard sales, craigslist, and consignment shops to pick up brand new/slightly used baby gear such as a swing, pack n play, clothes, etc.
When my hubby and I found out we were pregnant, both times, every time I went to Walmart/Target I would pick up 1 package of diapers or wipes. After 9 months I had a stockpile built up and both times didn't purchase a single wipe or diaper for almost 3 months!
Formula is very expensive, but buy the powdered type where you add water yourself and not the premix stuff b/c it is a lot cheaper. Plus the Parents Choice (Walmart) brand is half the cost and is the same as the name brand type. They even sell organic, soy, lactose free, etc. if you end up needing it.
Daycare is the biggest expense my husband and I have (3 yr old & 11 month old). For part time care (with a discount) it still runs us $1200 a month (way more then our house payment)! We figure we'll be rich once they start school, if we decide to send them to a public school. Make sure you check with daycares in the area and ask about corporate discounts if you or your hubby works for a larger local employer. Some will give a slight discount if you ask, but they typically don't advertise it. Also if you know about when your adoption will be finalized, get on a waiting list of the daycare of your choice. In our area, it is common for many of the nicer daycares to have up to a year waiting list to get in.
Otherwise, you can visit and call around for what the average cost of daycare will be, budget for diapers/wipes and clothes monthly, and budget some for increase medical costs.