Is the WD My Book 3TB USB 3.0 worth $99?

Please be aware that whether you set a password or not, it always encrypts the data.
This means that if the USB to SATA interface becomes defective in any way, you can't just rip the drive out of the case and put it in a docker or into your computer and hook it up directly and be able to read your data.

So far Western Digital's stand point on this is that they don't care. If it's under warranty, they won't replace the board, they will only replace the whole unit - guaranteeing that you don't get your data back.
They won't sell you the board so that you can get your data back.
They have no software decrypter that will allow you to get your data back.
If you send your drive to any data recovery house other than the ones that pay them to be authorized, you void your warranty.
If you send your drive to an authorized data recovery house, be prepared to pay $600-$1400
Basically, WD doesn't want you to get your data back unless you are lining their pockets - and they make sure you can't get it back as much as they can without blatantly doing it in a way that makes it look as criminal as it should be.
Also, if you DO put a password on the unit - the password is stored on a sector of the hard disk you cannot normally read.
This means that if the password sector becomes corrupt - if you had no password, it will suddenly be asking for one, and if you did have a password, yours will no longer work.
Western digital has no way to blank out the password, reset it or retrieve it (and if they do, they aren't telling us).
So in the case of password sector corruption, you are screwed again, since even if you didn't have a password, the data is still encrypted, and you can change every board on your drive, but it will still look to that sector, and want the password that you cannot possibly guess anymore.
Basically, the drive is designed to prevent you from retrieving your data in the event of any kind of failure whatsoever unless just the drive's own interface fails - in which case getting an exact match down to the firmware revision may save your drive and data.
The likelihood of this of course is fairly slim.

It is a good price though, so if you get an external eSATA or USB 3.0 docker or mount the drive internally - then yes, rip the drive out of the casing, and use it in that so you don't have to put up with WD's criminal "encrypt no matter what" policy - however, this WILL void your warranty!