Specifically Aomori or Akita?  Specifically walking distance from train stations?  I know it's a long shot, but someone might know!

I suppose Book Off goes without saying?

It could be wrong, but it doesn't look like there's any Book Offs north of Fukushima, so Joe would be out of luck on that front.  Cursorily looking at maps doesn't indicate much, though there is an Animate in Aomori so that might be worth checking out.

There are lots of Book Offs in Aomori, Akita, and Hokkaido, but none of them ended up being near enough to train stations that I could get to them in a reasonable manner.  Plus, ya know, normal sightseeing.  The towns I went to have all been terrible compared to other parts of Japan I've been to for games/CDs/collectibles.  I checked out an Animate in Akita near the station in a super sad old building that looked like it used to be a department store... now there's a very frumpy recycle shop on the first floor, Animate on the 6th, and no tenants at all on any of the floors in between.  The Animate did not separate game music from anime music, and the ONLY game album I found was from PSO2.  There was also a Tower Records nearby that had exactly 3 CDs in their "game" section. 

On a positive note, Hakodate is a really cool little city!  ...even if my nerd itch didn't get scratched there (that... sounds a lot dodgier than it's meant).

You would think google would put icons on all the Book Offs, but I guess it really just focused on Tokyo radiated out a bit and then maybe I would have had to add more search results to the map or had been more specific.  I didn't have much luck with game music at the Animate I went to in Tokyo either, so guess not much difference there.

Book-Off would have scratched the itch I imagine, a shame you didn't get to one. It's true game music isn't really on the radar up there - I didn't find much even in Sapporo.

I've spent some time in Hakodate too and it sure is nice. I recall Lucky Pierrot for lunch and a magical ropeway trip at night

Did you go to Otaru at all? There's a music shop there right across the road from the train station where I once got a bunch of sealed Digicube releases, which had obviously been sitting on the shelf for over a decade, for their RRP (one was Front Mission 3).