I don't know any specific places in Cherry Hill, but have you tried paintball stores or fire extinguisher supply stores. There is one called Boardmans in Collingswood, but I don't know if they fill them. I got mine done at a paintball store, but i'm in Burlington.
boardmans doesn't fill tanks. I go to two places. South jersey welding supply on route 38 (near carrabas) in maple shade. They swap out tanks. I also get my small 5lb refilled at camden bar supply on white horse pike and cuthbert blvd in oaklyn.
Thanks, the cheapest place I found is up in Trenton called Continental fire and saftey. I didn't get up there but the woman I talked to said $12.50 for a 5lb, might take the ride next time.