The most collectible Squier of all time
There is a particular old Squier guitar model that commands the most money...
...and that guitar is the Squier JV Stratocaster made in Japan from the early 1980s.
The reasons the Squier JV Strat is so desirable is because it's one of the best vintage Stratocaster reissues without it being an actual Fender reissue.
But - and this is a big but - the guitar is only worth something to you as a player if you like vintage Strats.
Some JV Strats have nitro finishes (others have a thin poly finish) which is cool, but many have 3-way pickup selector switches which sucks. Some do have the 5-way but the most desirable of the lot have the 3-way.
All the JV guitars as far as I'm aware were marketed as '52 Vintage for Telecasters, '57 Vintage for Stratocasters and also '62 Vintage for Stratocasters. They were made to play like real-deal vintage Fender guitars.
Did they have Fullterton California Fender pickups? Yes, and that's part of what makes them so desirable. But again, the JVs were specifically built and marketed as vintage Fender spec.
While true the JV from Fender Japan is the most collectible Squier ever, with some available for reasonable prices, I think the money is honestly better spent on a new Fender Standard Stratocaster, as in a Mexico made model. For around the same money as a JV, you get a guitar where you can change around the hardware if you want to and not have to freak out about it. You also get a warranty, which you obviously don't with the JV.
Or if you want to save a buck and get a seriously good maple-board Strat, see the Squier Deluxe Stratocaster. It's one of the few Squier Strats that has a satin urethane coated neck just like the Mexico and American Fender models do. It also has the two-point bridge with full-block brushed saddles. That guitar has some seriously good woods and hardware in it.
And of course there is the Squier Vintage Modified Stratocaster. There's a gloss urethane coating on that neck, but the price is nice, it has the vintage slotted tuners and the Duncan Designed pickups actually sound really good.
Real vintage Squier JV might be nice to have, but it's not really all that good of a player's guitar. And there's no guarantee it will get more valuable over time at any appreciable rate (meaning it might take 20 years before the value you buy it for now doubles... do you really want to wait that long?)