Buck and ball was around in colonial times. George Washinton even used it. You drop a round ball down the musket barrel followed by some buckshot so you have it all in one shot. Even near misses count.
Hand-loading your own shotgun shells would be cheaper but I've seen loaded buck and ball ammo for sale too. The best deal I've found is at the Sportsman's Guide. It's a .65 caliber ball and 6 #1 Buckshot. http://www.sportsmansguide.com/net/cb/cb.aspx?a=377126 Duplex loads are along the same lines but have buck and birdshot or two birdshot sizes instead of a slug or round ball in it.
I've have this same load in my FN Police Shotgun (Winchester 1300). I think it would be pretty effective in any situation. Buyer comments from sportsman's guide below:
Very impressive, will be ordering this item again in the future
JOE / KAREN L, FLOODWOOD, MN 8/27/2008 9:20:36 AM
Awesome
JAMES W, DERRY, NH 8/5/2008 1:49:48 PM
Awesome pattern at 25 yards.
KRISTOPHER, BRISTOL, FL 8/5/2008 8:37:35 AM
Good deal and good product
GREGG, FEDERAL WAY, WA 8/2/2008 8:56:07 AM
THEY ARE A GREAT SHELL
GREGORY R, SEYMOUR, TN 7/20/2008 8:33:34 AM
THEY WILL DO THE JOB
GREGORY R, SEYMOUR, TN 7/8/2008 9:48:14 AM
Perfect for when you can't decide between a slug and buckshot. Great performance.
CLIFF, KALISPELL, MT 6/3/2008 8:56:31 PM
I've never seen these anywhere else, and feel it's a great home defense round....hope I never have to try it. I'd feel sorry for whoever is on the wrong side of this load!
KEVIN, RIVERSIDE, CA 5/29/2008 10:11:20 AM