After competing in a bidding war last week, the sharks joined forces during the fourth episode of ABC's Shark Tank, handing over more than a million dollars to a husband-and-wife team of entrepreneurs.

Josh and Diana Harbour entered the tank seeking $600,000 for a 5 percent stake in their company, Red Dress Boutique, an online retailer that sells women's clothing and accessories at massively discounted prices. The Georgia-based startup saw its sales spike from $1.8 million in 2012 to $8 million last year, thanks in part to an aggressive social media marketing campaign that has attracted more than a million followers on Facebook.

"If you can come up with a way to automate this so you can scale, then you guys are going to go public," Mark Cuban told the Harbours before offering $600,000 but leaving the size of the stake open to negotiation.

Before they could counter, however, Robert Herjavec proposed a deal with Cuban where the two sharks would pay a combined $1.2 million for a 20 percent stake, an offer the Harbours jumped on immediately. 

"Two sharks are always better than one," Diana said. 

In another segment from episode four, novelty sunglasses company Sunstaches asked the sharks for $300,000 for a 5 percent stake, a valuation the sharks balked at despite the company's impressive $5.7 million in sales last year. 

"You're worth about two and a half million bucks," said Kevin O'Leary. "Nobody's going pay you more than five times your cash flow." 

After four sharks walked away from a deal--and FUBU founder Daymond John warned the founders they were "about to lose everything,"--the Sunstaches team agreed to give up 20 percent of their company to John in exchange for $300,000. 

As is often the case, striking a deal with the sharks requires slashing an overpriced valuation.

Stay tuned for more recaps every week.