That ability of Alolan Ninetales is certainly captivating. The ability to get any 2 item cards you want simply by evolving it (let's be clear, that's stupidly easy to do just like Zoroark) does look like it has the potential to increase the consistency of most decks. Grab your rare candies to immediatley get your stage 2's out (and you're probably using GRI Alolan Vulpix for it's Beacon attack so getting the pokemon into your hand, esspecially without N in the format since it'll be rotated by this point, should be pretty easy), you can also it to grab poké balls to get specific pokemon in your hand, tech in a friend ball or lure ball for specific scenarios, enhanced hammers if you need energy denial,
beast ring, actually, to get it the turn you need it, maybe even devolution spray if you have another Alolan Vulpix on the board so that when you evolve again you grab a total of 3 items (item 1 and devo spray from the first search and items 2 and 3 for the second one). An Ultra Ball or a Mysterious Treasure can grab a Tapu Lele to get a supporter and refresh your hand or get a Guzma the turn you need it. The versatility it has on it's ability, regardless if the attack / gx attack sucks or not, seems pretty good if your deck is devoted to using it.
If we're talking price, that can very well depend on what the metagame looks like in the future, what decks and what types are typically used. I think the new promo Solgaleo-GX coming out next October will be around by the time this Alolan Ninetales will come out, which means I can take a free two prizes simply by attaching a DCE to Solgaleo and bring it up to the active using Guzma. Scenarios like that can greatly change it's playability. I don't think it'll be anything like Tapu Lele, it might as well reach the same price as Zoroark if what I exaggerate about it's consistency becomes true, maybe a little higher if it's not coming out as a promo. Then again, it's a one-time use ability unless you actually use Devolution Spray so that matters as well.
Oh, just now read you we're talking about the
water alolan ninetales going up in price
Well it can use that card much more easily since it already runs Alolan Vulpix, but I think that can depend on the Fairy Alolan Ninetale's attacks and if Fairy Alolan Ninetales will be better in other decks. I'd say a maybe, more like a 50-50 chance that it'll go up in price, probably only like a couple of bucks higher.