Adopting a child via a social service can cost less than $1,000; Privately though, adopting in the USA can cost up to $40,000, while international adoption may cost around $30,000. These fees are due to the endless paperwork involved. More and more banks will lend money for this purpose.
Keep in mind that many with just average incomes are adopting annually. If you have loved ones who are generous and can afford to lend you the money, by all means ASK, and you stand a good chance of your request being granted.