Vito saxophones are annoying because several companies made them.
If your horn is stamped "Made in Japan," it was made by Yamaha and the horn's a stencil of a Yamaha YTS-23. If it's stamped, "Made in Taiwan," it was made by Jupiter and is a stencil of whatever horn they were making back in the mid-to-late 1970s. Further, the serial number on your horn dates to 1975ish if you're using a Yamaha serial number chart -- and you say you got it in 1978, QED that you probably have a YTS-23 stencil.
Anyhow, if you're talking monetary value for a Yamaha YTS-23, one in good condition is worth about what you're asking, but you can also find a lot of closed eBay ads that are much, much less than that. If you accept the maxim that ANY sax you buy on eBay (or Craigslist) has at least $300 damage to it, you can understand why you're not getting too many views. However, in my opinion, as a person who's owned a YTS-23, it has a playability value much higher than its monetary value.
I again point out that you should call Music Remasters and ask what they have. They're warrantied horns. They're cheap. Hey, at least buy a $325 B12 from Dave at JunkDude.com. If he says the horn's in excellent condition, the horn's in excellent condition.
Yes, I'm the Artist Formerly Known as Saxpics.
If you need me or just want to chat, e-mail me @ thesaxinfo-at-gmail.com.