Hmm. Good question.
For me, the over the top collector's editions do nothing for me. Take the Gears of War Marcus Fenix statue as a prime example. I can't play with it, it's too big for a normal shelf, and the price doesn't justify what I'm getting.
That being said, I do love the collectors that are only an extra ten-or-twenty bucks on top of the RRP.
So with that price point in mind, here's what I would like:
A toy is an obvious choice. Sacred 2 (although the figurine was awful) had the right idea. Maybe just a small statuesq figure that around five inches. Now that would fit on my shelf, hell, it might fit next to my copy of Dragon Age III.
I'd also like something that benfits me as a player exploring the new land you set out in front of me. Maps are great, but when it's just a coloured version of the in-game map, it gets a little bit predictable. Instead, why not have a map with points of interests on? Why not a map that has colour-coded areas telling the player that certain areas have better drops, or bigger enemies?
Okay, that's a terrible idea, but I'm sticking to "something that benefits the player" on their journey. I'm sure you guys could come up with something that fits the bracket better.
Randomly, what about necklaces? I would proudly wear the Kirkwall logo as a pendant on a chain, that came with a collectors edition. It would be like the Dark Mark, a way for Dragon Age fans to identify other fans. In fact, I could run up to people and shout "WHY NO MORRIGAN!?"
Perhaps scratch the last part, but you get the idea.