So I never owned a 360, I had a PS3 and a Wii last gen. Now I own an Xbox One and as such a live membership. I've been pocketing all these 360 games with gold since I got my Xbox One. I've decided I'd like to pick up a 360 to plug into the bedroom TV when the wife is using our living room TV. There are quite a few games I haven't played in that list. I also via giveaways and freebies happened upon a few physical games; GoW1,2,3 , Earth Defense Force and Binary Domain

I have a spare hard drive that is ready to go now they've added support for up to 2TB so buying a device with a bunch of storage is not an issue. Currently the 4GB model retails at $179.99 here new (the new Xbox One esque E Model), or EB do the previous model used for $109 but a bit dubious about picking that up.

is the 360 still a growing concern that they would even bother to give time to it or is just as likely to shuffle on to it's inevitable death.

At this point no. The retail prices for old consoles are going to stay how they are. It's up to the specific retailers themselves to put them on sale if you want to get them at a lower price.

I believe you can only store 360 games on one of their proprietary HDD's, not an external one.

@believer258: that used to be the case not anymore!

From what I understand external HDD's are in the same category as USB flash drive So only thing I'm missing out on is original xbox games (not an issue as I already own one) and MP3 music files which doesn't bother me either.