"$689.99

I might be able to get together a few more bucks for a good gun. "

Hey partner, if you can dish out $700 you've opened up a lot of possibilities for yourself! You can buy a rifle, weather it's bolt action or a lever -gun that can just about stop a griz in it's tracks!
You can buy just about any bolt action Winchester and Remington makes for close to that, in a caliber that will take down an elephant on an african safari.
You can also get a Winchester lever gun in the powerful 444 or 450 Marlin, or you can get a Marlin lever gun in either of these calibers, plus Marlin offers the 45-70 in theirs.

That is the route I'd recommend. If a griz is running at you a 30-06 WILL kill him, BUT a big bore lever gun or a shotgun will stop him faster (in my opinion) plus one of these will cost you $500 or less. And if you've never shot a lever action rifleyou will appreciate the speed at which you can sholder them and geta few good accurate shots off, and most of these big bore guns will hold at least 5 or 7 rounds.

Again I'd almost say, please don't get a semi-auto. You may be able to fire 1,000 rounds through it without a jam, and with some of today's quality guns you can exceed that but it will jam up at one point or another, and that time could be when that griz is coming at ya!