orcishgamer: The lead Runic dev told me last year that they got about 6 dollars off Torchlight boxed retail, 14(ish) on Steam, and 18+ off a purchase from their website. Off a game that retailed for 20 bucks that's quite a variance. You may extrapolate from there.
StingingVelvet: Cliffski, the developer of Gratuitous Space Battles, said much the same thing recently. Actually he acted like boxed retail was not even worth the trouble.
Which again is why I am torn. I want to support PC gaming and PC developers as much as I can, which seems right now to be digitally. They get most of the money, they get it right away and they don't need a publisher. That's awesome!
But I have this box addiction...
I saw in another thread that you didn't want to put half a foot in the all digital realm. I can understand this issue/OCD, I had it with DVDs, video games, and all kinds of other stuff. I can say, after you move your crap enough times the appeal of having crap wears off. Most of this crap, digitally, takes up so little room, I could carry all my crap on like 3 hard drives.
Still, I'm not like alia, I couldn't toss all my stuff, but the appeal of getting new physical stuff is dead for me (unless I can avoid DRM by doing it or I'm going to do game swapping with buddies, 360 games are like this, I'm getting to the point where I'll be selling all but the best ones once and for all, though).
I'm still in a state of transition and assessing my values on this one, honestly. I'll probably have made compromises that I don't even understand just now by the time I'm settled on a path. However being on the path of getting rid of physical stuff doesn't bother me. Generally I can still find art books, physically, which are nice and don't take up too much room relatively, I'm a sucker for art books.
I'd say just take the plunge for a year. I'd bet you won't have blown too much cash if you want to go back and physically collect some of it. You don't resell your games, you said, so going digital really is nothing to lose except a few feelies that in reality you won't care about nearly so much as you think you do (I bet).