I second what Kevin said.  Now, are they worth much money?  Good question.  But it would seem they're worth something, from your research.  Valor was not classically a highly sought-after brand back in the brand's production hey-day, but certain designs from almost any brand are likely to at least rise in value.  Given the Bowie style of this particular Valor, I'd say you found yourself one of those. 

And of course as time goes on, there's also likely to be some ebbs & flows in the nostalgia factor, which tends to increase value for a time, then after a while will drop off as those with the nostalgia, um, let's say "leave the market."

A Valor knife is unlikely to attain the status & price of a vintage Buck, Spyderco, or Benchmade -- but stranger things have happened -- depending on all sorts of factors (including condition, of course).  

Oh man...I'm glad I read my esteemed colleague's comments before entering my own...he literally took the words out of my mouth!

As a brand, Valor is collectible - for those who like Valor. The 559 is collectible - if you like "survival" knives. If your feeling nolstalgic and you finally get to purchase a Valor that you couldn't afford back in the 80's - then it's really collectible! As Kevin points out, if you like it, then it's collectible (to you).

By "collectible", are you really asking if it's valuable, or worh a lot? Well, sort of. There too it depends on how you are framing the value or worth. As you saw on Ebay, they cost as much today as they did in 1987, maybe a little more - but in much wore condition. That's true of anything vintage. 

Valor was a respectable mid-range knife company that made a host of knives that were "influenced" by other makers. I own a Valor 407dagger - a knife heavily influenced by the Kershaw 1007 Trooper. I didn't buy it because it's a Valor, or that it was made in Seki Japan (both collectable reasons). I bought it because I am addicted to daggers - and like you, it's hard to pass up a good looking knife at a great price! 

As is typical with me, I said basically the same thing as Kevin, but took twice as many words to do it. Thanks for letting me chime in. 

BTW - you have a VERY nice 559 there...and yes, it is collectible. :-)

Typical...just typical. In the time I spent crafting my original reply, DLKG snuck in there with his. At least we are all consistent in our comments. I would hate for you to walk away dissatisfied or confused by conflicting responses for a a valid question. 

And I still like your knife...well done!