Because nothing goes better together then winter and water balloons!

Why do two cost more than twice as much as one?

I foresee pain and suffering in relation to this giant slingshot.

@charlesp2009: Actually you are correct. I bought one of these about 12 years ago from a flea market when I was 15. We would attached both sides to fence posts so that we could just put things in the center and launch it way farther than it advertises. We would mostly shoot eggs and crap to a building down the street. Well one day like a retard I put a piece of glass in it (dont know why) and when I released it, it shot out but didn't come out of the holster and actually shot back at me. I have a 2 inch scar on my arm where it tore through me like...well a piece of glass.

These things can be very fun, but can be very dangerous if you do something stupid like I did. Also make sure you am it at a good angel because if the balloon hits you in the face its going to get you nice and high after you see the doctor for some pain meds :)

make sure you factor in the cost of the law suit

Be one with the melon. Be the melon.
http://www.youtube.com/watch?v=ZGPJQhPD4rs

Pharmacy:
10' Surgical Tubing (Heavy Duty Preferred) ~$0.35/ft

Department Store:
Waffle Pattern Washcloth ~$1.50

Hardware Store:
2x Small Pipe Clamps < $1.00
1 Roll Duct/Electrical/Other Tape ~$2.00

Outdoor Store:
1ft Nylon Webbing ~$0.15

Other Requirements:
Needle/Thread or Access to a Sewing Machine

Total Materials Investment: ~$8.00
Assembly Time: 1 Hour
Possibilities for Fun: Endless
Time In JJC: 3-6 Months

Tip 1: These can also be "self-fired" by putting your toes through the payload handle, and holding each of the tubing handles in your hands. If you reach forward far enough with your hands, you can even avoid getting hit in the crotch with whatever you are launching.

Tip 2: When launched from one of these, a giant Oregon slug disappears into a splotch of yellow goo upon impact... or so I have heard.

The formula for these go something like this:
a few bored men
copious amounts of a favorite alcohol
slingshot
water balloons
unsuspecting targets
The result was an all out battle the following day involving around 100 people and a couple thousand water balloons. It was glorious. (Wish I had taken some pics during the battle.)

Two screens into ordering but no Paypal halted the purchase for me.

How well does it work with small furry animals, like cats?

These will break a windshield in a car! :(

It works very well with snowballs too

Good deal, but does this come with a Get Out Of Jail Free card?

Yes, if you shoot it flat it shoots pretty hard and fast. It does suck to hit someone you weren't aiming at. And it's not hard for them to figure out where the balloons came from.
However, shooting up (like a mortar) and dropping water balloons onto people with no idea of where they come from is great fun. You could pop two or three up there, and be turned around before anybody notices anything happen.
And winter is a great time for water!

Ordered 5 days ago, hasn't shipped yet.