Originally Posted by
cyclist2000
Any derailuer should work. A cheapy is around $25.
No, it really won't.
You need specifically a "Shimano Tourney rear derailleur with hanger". $25.00 would be on the high side for that derailleur. $15.00 would be more typical. Installation is about a $25.00 job but may run a bit more if it's necessary to replace anything else (like the shift cable and housing).