Like olddude said - youth groups.

They're always needing money. Maybe you could collaborate with them when they're doing a yard sale. Have a drop off area for broken electronics. Prior to the sale you would have the teens tell everyone they know to bring their broken/unwanted electronics to the sale.

It'd be like a mini army of people spreading the word.



And who doesn't want to help a teen go on a trip? It's a win/win for all.