Maybe I can understand the older than 18 months, but telling me that 6-18 months old data is already on tape backup in a far away storage facility is ridiculous.
Sure they have moved the data to backup servers which might not interact with aa.com anymore, but there should be no manual labor costs involved. oh, im sorry, the cost of a few clicks to point to another server and entering an AAdvantage number counts as labor costs.
Its a ripoff! They know there must be some compelling reason for you to want those records and most likely you are going to pay if you really need it.