The picnic in Williamstown also raised reward money.
Matt Novak's killing in Philadelphia, two years ago on September 28th, 2008, remains unsolved.
Police say Novak got into a Blue Chevy Impala after his own car broke down.
The people in the Impala then shot Matt and left him at 13th Street and Fairmount Avenue.
Surveillance video showed the Impala leaving the scene.
His father, Matthew, misses his son and wishes that the crime would be solved.
"Call the Crime Commission, it's an anonymous tip. If it leads somewhere, you get the cash, but please help us. If it was your loved one, I'm sure you would want to know who murdered your loved one," Matthew Novak said.
The Impala had New Jersey tags but are unclear in the photos.
Call 215-546-TIPS with information that might close the case for the Novaks. There is a reward for up to $20,000.