Wow, $69 to replace the battery, that's ridiculous.  In case anyone does not understand, that's called sarcasm.  You've spent $700 to $1000 for a phone and you are going to complain that the price to replace the battery might be $10 0r $20 dollars more from an authorized service center?  I'm sorry, but I am willing to pay more to be sure that the work is done properly.  While that's not a guaranty, and independent service centers probably can do just as good a job, it just doesn't seem worth it to me.  Apple is just reminding you that they didn't do it, so don't complain to them if something goes wrong.  Remember, a message is just a message, and it doesn't keep you from doing it.