Okay let's be very generous and assume that theses guys are financial geniuses. Wizards even. Let's say they've figured out some way to generate a steady 30% annual return on their investments. In that case they'll see $8.75 from my $100 binocular purchase.
Sure they'll see this $8.50 multiplied hundreds of times, but as Hector13 pointed out they'll also see the associated costs multiplied by the same amount. The economies of scale only save you so much. And if you're losing money on each transaction, that scale is working against you. "Yeah I lose a buck fifty on each sale but I make it up in volume."
There is no way that $8.50 is going to cover their cost of doing business for that item. Again, just getting me a rebate check is costing about $3.50. I used to deal in sporting goods sales, I know the binoculars must cost them $15, even if they get a great deal 'cause they buy a boatload of 'em, we're still talking considerably more than $8.50. And then there are the rest of the many, many costs of running an operation of their size. For example they pay 7% commission for referrals. Right there that almost wipes out the $8.50.
And don't forget the man hours it takes them to process each rebate. I transposed a couple of numbers on my rebate, and they caught the error and sent me a snail mail notification. That kind of attention doesn't come cheap. (I still got my rebate, see earlier post)
And I doubt they're getting 30% APR. If they could guaranty that kind of return I'm sure they would hang out a shingle that says "Investment Bankers", move to the South of France, and not deal with a bottom feeding, deal hungry, pain-in-the-a$$ Anandtecher like me. If they could earn a consistant 30% the statue on Wall street symbolizing good times would not be a bull, it'd be the Cyberrebate frog.
I still think they depend primarily on people failing to send in for the rebates to earn their daily bread. And the meat for that bread may come from the not 100% rebate items. Mangling the meal metaphore once more, the "float" might cover the salt & pepper.
But I could be wrong. In the mean time, enjoy the rebates but save a copy of everything!
