Praise the Lord that we are not limited to three. I'm more of a fowling piece collector. However, on rifles, I like to have one of pretty much anything that comes down the pike, from .45-70 Government to 6.5 Creedmore. Of course, .243, .30-30, .30-06, .270, and pretty much everything in-between that there is, I need one, just to round things out.
00 Buck has fallen in price. Not as cheap as it was three years ago, but around 1/2 price of its peak. When the black lives matter terrorist insurrection acts commenced, many ran out and picked up a slide action 12, for home defense. Along with that went the 00 Buck. A box of five was running 10-15 dollars. Now, the standard box of 25 can be had for under 20 dollars. And, with any type of quantity (some as low as only 120 rounds), pricing can be found for around 40 cents per. Check out "ammoseek" or Wiki Arms.
For ferral pigs, it doesn't take much. I know many that swear by .223 Remington, due to them being relatively inexpensive. Bear? Many black bears have been taken by the old .30-30. I carry an 8 3/8 inch barrel revolver in .454 Casull. I have never shot a bear with it, but it gives me some feeling of safety when I'm in parts where they roam. You can keep your spray.