Hi Mike...
The .243 and 30/30 and 7mm/08 are all fine for the hunting you describe, including black bear. The 7mm/08 is actually quite a bit more power and muzzle blast than you would need so it might teach you to flinch a bit.
Ammo is readily available for all three. For the .243 you should use the 95-grain or 100-grain bullets and for the 7mm/08 the 140-grain bullets will be great. You don't need any of the expensive "premium" ammo for deer. The regular ammo you find at Walmart from Remington or Winchester or Federal will be fine.
The .243 and 7mm/08 are available in a splendid deer rifle - the bolt-action Remington model Seven. It's a bit pricey but you might find a used one.
BE SURE to check the laws to make sure you can use a .243 for black bear. The non-geniuses at the so-called Game Dept. may have some silly restrictions on calibers that can be used for black bears.
The 30/30 is easiest to find in the lever-actions - primarily the Marlin 336 and the Winchester 94. And the Marlin and Winchester lever guns will be a lot less expensive than other action types - especially if you buy "used". I just bought a very nice Winchester 94 for $225 tax included and recently bought a mint-condition Marlin 336 for $250+tax.
At the ranges you stated you might well not need a scope but a low-power (2x etc.) sure brightens dark areas as well as early and late in the day. The Marlin 336 is easy to mount a scope on. The Winchester 94 is not really designed for a scope and is a PITA to put one on.
On the downside - scopes kinda interfere with the wonderful carrying qualities of the lever guns.
If you decide to stay with iron sights on a lever gun I earnestly advise you to get a set of Williams 5D aperture sights for it (about $45-$50). They are 100 time better than the sights that come on those rifles from the factory.
A better question to ask yourself is whether
you would handle a bolt-action or lever-action better. If you don't know, visit a gun store and try one or two of each. Remember that fast shots are not really often a part of ethical game shooting. Always make the first shot count... or don't shoot. It's more important that the rifle feel "natural" to you and is lined up well when you shoulder it.
The two common bullet weights for the 30/30 are 150-grain and 170-grain. Many people think bigger is always better but in this case "bigger" is nothing but more recoil. The 150-grain bullets are fine for both deer and bear.
For the hunting you describe, I would probably opt for one of the lever guns in 30/30 with a Williams' aperture sight.
One of the other posters mentioned the .35 Remington cartridge in a Marlin lever gun. That caliber has been cleanly killing deer and black bear for decades. But as they said - "it's a "thumper" - but it's a "thumper"
on both ends so keep that in mind.
The .243 and 30/30 are two of the
very best deer calibers you can buy. That's the easy part. Finding a rifle type that suits you at a price you want to pay is where the work is.
Good luck !
