The way I did the GNR was not very expensive at all. I sent him a 357Mag barrel from an H&R Handi-rifle. He reamed the new chamber for $125 and the dies were (IIRC) $75. Even with shipping, I still have more in the scope than I do the rifle.
I got 200 Starline cases from Blue Star Cartridge and Brass for $88.84, plus $14 S&H. Case-forming chores were the simplest I've ever experienced, for a wildcat: Lube the case neck, size the case...done. No fire-forming is required. The 445SM is rated for ~40,000psi and necked down to 358GNR has an internal capacity of 45gr H2O.
I don't really want a rimless case because I'm shooting from a single-shot gun with a standing breech; rimmed is better. For a lever-action, tubular magazine, rimmed is also preferred. I have found 6.8SPC brass to be more readily available, but actually more expensive than 445SM, which is typical of bottle-necked cases. I would certainly just use 30/30 brass to form 357Herrett, which would be about the same process I use to form cases for my 30 Herrett barrel. In fact, a 30 Herrett opened up to 35 caliber is what you'll wind up with, depending on how you look at it.
I think the 460 S&W, shortened .175" would be an absolute hammer on Indiana deer. It is certainly enough gun for any distance at which we might hunt deer and as far out as trajectory would allow, there are several .452" bullets that would pretty much flatten even a large buck. The 200gr FTX would be my first choice, for its better BC and lower recoil level. It would be no trick at all to have a 460 cut with a short throat, or to just seat the bullet out a little further and/or have a longer jump to the rifling. I'm acquainted with an exceptional gunsmith who has already built a couple of rifles along these lines.
The 357 Max (
http://357maximum.com/ ) is by FAR the easiest, least expensive way to get into a very good Indiana-legal deer rifle. Any other chambering is only going to improve upon it by, at most, 25% and as you pointed out, that just isn't a big deal when the Max is already good out to 200-225 yards. (You state that you're comfortable with it out to 250 yards, but with the 2100fps velocity you're getting, I'd have to see the ballistics chart to understand how much hold-over is involved.)
I prefer to hunt with a long bolt-action rifle. A Model 70, Model 700, 110, etc. just feels right, when I'm in the woods or up in a tree stand. It's how I grew up and what I'm comfortable with. I like lever-action rifles as well, but mostly just for fun shooting.
What feels closest to me, w/o spending $1,000, is a single-shot like the Encore or H&R. I have come to enjoy those quite a bit.