I know they are somewhat rare, but tell me, how much is my 1984 Alvarez Yairi DY73 worth???

To me, very little, only interested in how it sounds. Cheers
In that case, it's worth a good deal, out of all the guitars I own(Taylor 714 Grand Auditorium, Gibson J-45, Fender Telecaster), this one has the best sound.
It's worth whatever somebody will pay for it. Check eBay to see what they/similar models have sold for.

Why on earth would you want to sell a Yairi? I will own mine until I die. Hands-down, my DY-76 is the best sounding, best playing 12-string I have ever played.
Guitars: Carvin TL-60T, Carvin C750 Acoustic, Squier Strat w/Carvin C22B & AP11's, Alvarez-Yairi DY76 12-string, Eastman MD-605 Mandolin, Fender Mandocaster, Ibanez UKS-10 Ukulele