M.,
My own child isn't on the spectrum but my nephew is so I pay close attention to this issue (since it's been at least partially gentically linked). Right now, there are hearings happening in Lansing (the next one actually takes place on Tuesday!) to try to get legislation passed, requiring insurance companies to cover autism spectrum treatments. They're even asking for parents to testify how ABA has helped their kids (you can either testify in person or in writing). There are currently 14 states who have already passed this kind of legislation and if I remember correctly, Minnesota is one of them (which is likely why the family you know there has things covered). If you can find the time (I'm sure that your life already is insanely busy - but good for you for seeking the help for your daughter!) you may want to try to get involved in the group "AIM" - Autism Insurance in Michigan. They are fighting tirelessly to help get this legislation passed and they're currently making some huge strides. Even if you can't attend rallies or hearings (I can't), you can still write to your congressmen/women and state senators (which I've done). Their website is http://autisminsurancemi.blogspot.com.
Have you also considered coupling the ABA therapy with a nutritional approach? This has worked WONDERS for my nephew. He started with the ABA and made some progress but when his diet was adjusted (removing wheat and dairy and taking nutritional supplements), he turned into a totally different kid. His diagnosis actually improved from PDD-NOS to Aspergers just recently. The book "Healing the New Childhood Epidemic: AUtism, ADHD, Allergies, and Asthma" by Dr. Kenneth Bock outlines the program and offers many real-life cases of how the program helps along with therapies like ABA. My nephew's own DAN! doctor is one of the cases in the book (her daughter).
Best of luck to you - I can't even imagine having to make that decision to sell a house to cover therapies that SHOULD be covered! Hopefully the tide is shifting and you will see some positive change in insurance coverage in the near future!
I also would like to reccomend Jenny McCarthy's most recent book "Mother Warriors". It's truly inspiring to read about parents who are so dedicated to their kids' recovery!
Bless you!