Very important. If you have someone else do the repair, make sure you have your own full complete backup. Even better have 2 full complete backups by 2 different utilities to 2 different backup devices. Repair facilities have been known to loose your data. Do not depend on them doing the backup for you.
Also if you have sensitive data on your device, ask them to return the replaced device along with the repaired Macbook, and you can securely dispose of it when you no longer need it.
$200 would most likely be in the ball park. You will not know until you actually ask Apple, or whatever replair facility you decide to use. Chances are the cost of the disk will more than what you can get on-line. And labor charges are not cheap.
Piggy-backing on Eric Root's suggestion. It is not that difficult if you have the correct screw drivers and torx bits. I've done this to my Late 2011 15" Macbook Pro. But in my case I replaced my rotational hard disk with an SSD and my Mac is faster than when it was new.
I also upgraded the RAM to 16GB (OWC <http://MacSales.com> and <http://Crucial.com> are well respected Mac RAM vendors).
Tools can be obtained from OWC <http://MacSales.com> or <http://iFixIt.com>
You can find lots of YouTube videos so that you can compare and contrast the effort needed.
As mentioned by Eric Root, OWC has lots of do it yourself installation videos.
And <http://iFixIt.com> has teardown instructions you can print out (I find it useful to tape each screw I remove to the instructions, so I know where it goes when I put the Mac back together again).
A 480GB SSD with tools and an external enclosure for the old internal drive goes for $200 from OWC
A 500GB rotating hard disk with tools and an external enclosure for the old internal disk drive goes for around $60 from OWC.
You want the external enclosure so that you can first put the new drive in the enclosure, then use Carbon Copy Cloner (1 month free full featured demo) or SuperDuper (always free to clone the entire disk) to make an exact copy of your internal disk to the new disk before you install the new disk.
You could be ordering the replacement drive before you head home, and depending on how long until you get home, and how much you want to pay for shipping, it could be at home when you arrive.
Just a thought.
