GreenSky noted in their end of the year earnings call that their acquisition costs were among the best in the market; during the call GreenSky showed a chart pointing to the fact that costs were lower than PayPal and Square; deBanked broadened the list and compared GreenSky with Square, PayPal, OnDeck, Prosper and LendingClub; the data shows GreenSky has the lowest costs at 5 percent and prosper is estimated to be close to 75 percent; year over year the numbers are pretty steady with GreenSky staying at 5 percent. Source.