hypothetically speaking, one of these might work:
Air Pellet Rifle - Cheap!hypothetically, one might buy two or three, because they're so inexpensive, and shipping doesn't change that much for the second and third ones.
hypothetically, one might sit out on the back porch and take out squirrels out to thirty yards, swiftly and humanely (with a cheap $7 scope).
I think the pellet speed quoted might be a lot on the conservative side.
Hypothetically "hollow point" pellets work best.
{Caution: squirrels are technically considered a game animal, and it is illegal to take game in Texas with any pellet or air rifle -
Means and Methods link}
edit - nevermind. I just saw that you're in NJ. That pellet rifle can't be shipped to NJ. Maybe you can find one for sale locally? The Texas hunting laws obviously don't apply there, as well.
[This message has been edited by TX AG 88 (edited 9/11/2007 10:32a).]