Yup 2/16-2/22 the Blu-ray/DVD/Digital version will go on sale. Click on the respective link to let them know about the lower price, and hopefully they'll match (though without the bonus disc of course).
The $29.99 price is in the ad for 2/16 which is the week it's released. The price on their website will not reflect the $29.99 price until the Sunday before when the ad actually starts. You can follow the link below and see the ad for yourself.
Yeah, the bonus disc from target is kind of worthless. If you keep up with the latest game of thrones news and stuff, you've probably already seen it and it's mostly just pointless Q&A with actors mulling over past plot points or filming info that you may have already heard or could probably find out through episode commentaries and such or you could just watch it on youtube. The bonus covers for the best buy version aren't very appealing either since they are just the same Stark, Lannister, or Targaryen covers from Seasons 1 and 2 with "The Complete Third Season" printed on them instead. Wal-mart has a bonus disc available too. It has a a featurette about visual effects, but they aren't selling it for $29.99. Although they would probably price match it in store. Amazon's limited edition dragon statue case is nice, but far too overpriced at $89.99.
I'm glad I forgot to change my card info for my preorder of the Amazon limited edition and it got declined. When I ordered it there was only a $20 price difference not $60, and they were talking about more stuff was going to be added to it. $60 more for a cheap plastic case isn't worth it no matter how great the show.