I'm no help with the O/P question but......
Just purchased factory refurbished Garmin 5212 from Get feet wet . com.
There are a few smaller refurbished units listed on there site.
Links below....
Garmin498 internal antenna and transducer...$475 or without ducer for $425
http://www.getfeetwet.com/products/S...-N0504-02.aspx
They also have a 545 garmin for $580
http://www.getfeetwet.com/products/S...-N0601-00.aspx
A smokin deal on a Garmin 3206.. $699 ( however you will need a gsd21 to get it to fish finder/depth). It can be networked and do radar over chart.
http://www.getfeetwet.com/products/S...-N0527-00.aspx
Always have purchased refurbished units and never had a problem. Previous boat had a refurbished 3010c garmin.
Our V 20 has a Garmin 192c.