Assuming three lives per quarter, you can die 720 times in Dark Souls before you'd have to spend more than its original retail price of $US59.99. Yet, I think 720 deaths might be on the low side for most folks in this game.
deviantART user semsei imagined Dark Souls as a 1980s arcade cabinet promo flyer in this brilliant poster. It proclaims "10 different classes, 27 amazing locations, 26 bosses, 0 hand-holding." Also, remember to use these buttons to not die.