I've seen patches and shirts in antique malls - not individually owned stores, but the big places that rent space to many vendors. One or two of the vendors my have some stuff. Military old stuff seemed more common, though.
[edit]If by "other than places like eBay" you mean not online, then don't google "boy scout" & vintage. I don't collect this stuff, but I just tried googling and found several interesting links
here.
One interesting item is a
vintage photo of boy scouts in formation, circa 1900![/edit]