Just a quick chime in...
The Bass VI low E is actually the same pitch as a standard electric bass, so the E,A,D,G are pitched as a bass guitar - then it adds the B and top E strings. So is strung in the same way as a guitar but obviously lower in pitch.
I believe the idea of these was to aid guitarists in playing bass parts, but strictly speaking they are not the same as the baritone guitar which may be more suitable for you? They are tuned to a C just below the normal guitar pitches so work well when strummed.
I have three vintage Fender VI's at the moment, and they are great instruments, they can really add something. The bass part can be played on them and then any soloing on the top strings is like playing a guitar (but more mournful sounding - think high range of tenor sax).
Anyway, these are very good basses indeed and it's a very fair price. Good luck with the sale.