Head over to Zulily's Just For Dad Boutique and check out the Father's Day gift ideas good through 5/14 (6am PST) at fantastic prices! This Zits Tribute-ish to Fathers an Sons is just $9.99 (regularly $17).
Or this Ball One Perfect Game Boy Set, $16.99 (regularly $30). They also have these sets for girls (with pink stitiching) and for twins!
This Kangaroo Two Pod Charging Station, $9.99 (regularly $20) is available in black (as shown), white or bamboo. Just sign-up/login to Zulily to access these items and look at others that might catch your eye and bring a smile to Dad's/Grandpa's face.