As with any collectible it depends of supply and demand.

So yes, prices for certain titles will go up especially if the supply is very limited and it's a very popular, sought after title.
Sometimes, they won't really go up at all when they are mass produced in great quantities. For example all of those Star Wars Steelbooks which I see just sitting on the shelves about a year or so after release.

The only bad thing about Steelbooks is that either can get dented or the paint will scratch off. But I believe that there are protectors one can buy to put them in to help protect them.