Ooooooo, I'll play. If we are allowed to have multiple barrels for a gun:
1. a .357, use .38's for practice (hd) (brand agnostic)
2. a 22lr bolt action rifle for working on form (plinking, practice) (brand agnostic, but I like mossbergs) (cheap will work)
3. a T/C encore or CVA Optima elite with: (350 for the optima with 1 centerfire barrel, barrels are about 200 each)
1 .50 cal Muzzle loading barrel (just for the experience)
1 .308 win., 30 -06, or 300 win mag barrel (big game, varmiting)
1 .223 or 243 barrel (varmiting)
1 12 Ga barrel (water fowl, game)
4. a mossberg 500 (HD, trap, hunting) (300 for this setup right now)
1 smooth bore with full, mod, and cyl chokes
1 rifled barrel for slugs
5. .50 BMG (why the heck not??) (hey, a guy can dream can't he.... the top four cover all needs and can be done for around 1200 total if you only have one centerfire barrel on the optima)
If we can't have multiple barrels
1. any .357/.38 (hd / range fun)
2. Mossberg 500 with a smooth bore (HD, hunting, trap) (about $200)
3. any .22lr or .22 mag (to work on technique, short range varmiting, plinking) (about $150)
4. savage 110 .308 or 30-06 or 7mm mag (big game hunting, long range target) (about $400)
5. .223 or .243 for varmiting
again, your five guns very well could end up less than $1200 dollars, especially if you are willing to use iron sights.