For most people you will not have to worry about the cost. Your health insurance provider should be able to cover this. Talk to your doctor is the best way to find out if this is applicable to you.
For everyone else, the cost will start at about $1000 for the complete surgery. Some places will actually offer you a two night stay with them as well as other amenities. You may even be offered transportation to and from the airport if you've had to travel by plane.
The cost of lap band surgery is really going to depend on what you want and how far you have to travel.