This is a simple parts swap. Locating the sensor is probably the most difficult part. As with all repairs, the only price that means anything is the one quoted by the person willing to do the job. If you were close by me and dropped by with the sensor in your hand, a cold beer would be payment enough.
The vehicle speed sensor (VSS) is on the transmission of all vehicles.
The 2008 Subaru Forester has a 5-speed manual.
The 2006 Subaru Forester has a 5-speed manual.
The 2014 Subaru Forester has a 6-speed manual.
The 2007 Subaru Forester has a 5-speed manual.
The 2004 Subaru Forester has a 5-speed manual.
The 2002 Subaru Forester has a 5-speed manual.
The 2012 Subaru Forester has a 5-speed manual.
The 2005 Subaru Forester has a 5-speed manual.
The 2013 Subaru Forester has a 5-speed manual.
The 2010 Subaru Forester has a 5-speed manual.
The 2001 Subaru Forester has a 5-speed manual.