Cheapest DXM item

Anyone know the cheapest DXM OTC? Robotussin is 8 bucks for 4 oz but I looked at drugstore.com and saw Benylin(sp?) is $3.79 or so for 4 oz with 15mg/5ml. Are there any other better buys for DXM as the only active ingredient? Anyone know anything about this Benylin stuff?

Look for the generic brand. CVS Maximum Strength Tussin is only 4 something for an 8 ounce bottle. The exact same thing as Robo, yet cheaper.