Well done, you sold 50,000 Baby Wee Wee dolls (hey, we're just picking a product at random here). Now what? You've acquired 50,000 Baby Wee Wee fans, not 50,000 customers. They only bought from you because they're big fans of (all too) anatomically correct dolls and you happened to be around to feed their need.
Wouldn't it have been better if you'd sold a handful of Baby Wee Wees, plus maybe some Breast Milk Baby dolls, some Pole Dancing dolls and... um, maybe some products that weren't massively inappropriate? Remember: volume sales needn't only mean selling large quantities of one single product SKU - in fact, you're never going to grow your brand or acquire loyal new customers if that's all your marketing sets about to do.
That's one of the reasons daily deal promotions don't work: you blow your entire quarterly budget on promoting one product and, at best, acquiring a very limited type of customer. Far better to spend a much smaller amount of money over a longer time, and acquire a wide range of customers who actually care about your brand and your products.
That's why we tend not to charge per Co-buy. Instead, for less than you'd pay to run just one daily deal on other sites, we'll license you the technology you need to launch strategic social commerce promotions for as many of your products as you like. That way you can develop your brand, not just one part of it. You can avoid discounting any of your lines to a premature death. And you can engage with your customers (and potential customers!) - asking them what they'd like to Co-buy, then tactically deploying promotions to achieve the greatest possible impact.
The power's in your hands. But, if you've been playing with a Baby Wee Wee, you should probably wash them first.