Hey, Kathy,
I didn't realize you were THAT Kathy! How the heck are ya!
People post about decks here as well as on the competing forum, United Cardists. They also check out Kickstarter a lot as well as the major deck retailers, not just the big magic companies like Ellusionist, Theory11 and Penguin but also card specialty places like PlayingCardDecks.com, Gambler's Warehouse's retail site and CollectablePlayingCards.com and places like that. Sometimes they go to the smaller magic companies, brick-and-mortar stores with a web presence. Sometimes they're on the designers' own websites, like Randy's and Jackson's and Alex's and so on. And of course, there's places like Kardify.com and reviewers like Ender'sGame and Magic_Orthodoxy, so yeah, they check out YouTube and Instagram as well. 52+J club members hear about stuff sometimes in the magazines we print on occasion, but a lot of our coverage is admittedly post-release rather than pre-release.
In short, it's everywhere. They do try to keep up over at UC, but there's just SO many new decks all the time. If you folks at Murphy's did some kind of consolidating of data, like posting a simple website with a regularly-updated schedule, perhaps tap a few reviewers to post about products, you'd do well with that, I suspect - not a retail site per se, but a site promoting the decks, announcing when they'll be selling and maybe even putting in a few ads from your retailers who are selling them. I think a site like that could really do nicely. Call it Murphy's Decks!