I realize you were asking about prices in the States for this procedure, but thought I would tell you about what our experiences in both Thailand and Mexico were like as compared.
First, neither of us had to do 3 days of prep. We were told to eat normally and live our lives in the same fashion as we usually do. Then, the day of the appointment we were to get up at about 5 am (to prepare for our 8:30 am appointment) and take this prescription liquid mixed with water. We ended up drinking about 2 liter's worth. By 7:30 am after being cleaned out, we drove to the hospital for our appt., received the anesthetic, got the procedure done and went into the recouperating room.
After waking, the doc went over our CD movies of the procedure and gave us copies for our personal doctor to have as a baseline. We had a complimentary ambulance drive home.
In Thailand, it cost a total of about $300USD, $500 USD if you wanted an endoscopy along with it.
Mexico was a little higher in price, about $500 USD for the colonoscopy. We paid out of pocket.
The biggest difference seems to be the one morning prep versus the 3 days of fasting and observing different eating behaviors. The price was a good value also.
Akaisha
Author, The Adventurer's Guide to Early Retirement