It's been a big week for 4K, with the network-based RedRay Professional 4K Cinema Player shipping from Red Digital Cinema and more of Sony's new Ultra HD TV sets showing up in the real world.

Red's Jarred Land took to the forums at RedUser on Tuesday evening to announce that deliveries of pre-ordered RedRay players had begun. Meanwhile, availability seems to be broadening for Sony's recently released 55-inch and 65-inch Ultra HD TVs, which list for $4999 and $6999, respectively. (Samsung is reportedly launching 65-inch and 55-inch sets this month in Korea, but not yet in the U.S.) Best Buy's website is showing a roughly one-week wait time for delivery of one of the Sony sets in the New York metro area. Mega-retailer J&R in lower Manhattan reported both Sony sets "in stock" this morning, as did

Scroll down in those Amazon search results and you'll see a set from a company called Seiki Digital for $1499. Your eyes do not deceive you — the Seiki SE50UY04 is an Ultra HD TV set that retails for what may seem like an extraordinarily low price. In fact, it was available for just $965.99 earlier this week. (You can track its price history here.)

Proceed with caution — reviewers have not been so kind to the Seiki set, with decrying its "skewed colors" and "poor shadow details," and Cnet complaining about "light black levels, poor screen uniformity, and subpar video procesing." A review at Heron Fidelity notes, "With 4K source material, the Seiki SE50UY04 looks damn good," whil HDGuru grouses, "The SE50UY04 is a mediocre TV that just happens to be 4K."

Judged purely on its price per pixel, the Seiki is a great deal. At $1500 for the Seiki SE50UY04 plus another $1750 for a RedRay player, you can have 4K playback for just $3250. But it makes a lot of sense to take that TV for a test drive first to see where you come down with regard to its shortcomings. (On the tenth page of that RedRay thread, Land suggests using an HDMI signal booster when connecting components to the Seiki.)

Meanwhile, Red's 4K digital distribution partner, Odemax, is allowing filmmakers to apply to become owners of content channels on the system by submitting a sample of their work. Odemax currently lists eight content channels at its website, including one for Red Digital Cinema itself. (For more on Redray's tech specs and what's been revealed about the planned revenue split between filmmakers and Odemax, see our previous coverage.)

As more 4K displays hit the market between now and the all-important fourth quarter selling season, the industry will get a better idea of how strong consumer demand for higher-def TV really is. If Ultra HD sets take off, broadcasters will have to decide sooner rather than later how they're going to upgrade their equipment to handle 4K transmissions. But if consumers remain generally happy with their HDTV sets, expect broadcasters to stay put at 720p and 1080i for the forseeable future.