I have one and have used it extensively from Maine to the Bahamas. It's slow compared to today's stuff, only gray scale, requires the CMAP cards and can't support any of the hi bandwidth stuff like radar integration, but it has been a good trooper. The radar screen I have in the cockpit will display the active waypoint so the 620 stays inside. It has been back to the factory a couple of times since purchased, but has been solid the last several years. I doubt that they support it any longer?
I am now using seaclear on my laptop as the backup. It will, via the seatalk to nmea converter, also send the active waypoint to the radar screen and it is easier (larger, faster) to set up routes, waypoints.
I don't know what you would pay for it, but consider the laptop with the free software and charts. Except for the ability to securely install the 620, the laptop approach is much better.
I wouldn't bother spending the money on it... it is only monochrome, as bhcva points out, and IIRC, Raymarine no longer supports the Cmap charts, having moved over to Navionics on their newer models.
I would highly recommend getting a unit like the Garmin 440 or 540, since they'll have the entire coastal US charts pre-loaded, and the updated charts are only $75 or so. Also, the unit User Interface is a bit better than that on the Raymarine.
Also, the screens on the Garmins are far more viewable than that of the Raymarine unit.