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.
Note: I'll only be around occasionally until December 2015.
If you need me or just want to chat, e-mail me @ thesaxinfo-at-gmail.com.