The Anker TC930 Ultra-Thin Keyboard Cover for iPad Air is very similar in style to the Logitech Ultrathin Keyboard Cover. It's not exactly a knockoff, but it's close: black plastic keys and tray, metal back, and magnetic attachments. The Anker keyboard one ups the Logitech keyboard with a pop-up stand that activates when the iPad enters the mounting slot, rather than relying on gravity for stabilization.
Logitech doesn't include bumpers on the front, and it has its own Bluetooth button rather than being integrated as a function key. All cosmetic choices. The keyboard layout is nearly identical, though the Anker keys are slightly looser feeling. I bring this up because in repeated tests between multiple brands, the Logitech Ultrathin comes out on top, primarily because of its excellent design. The differences in tray and feet quality are external to the TC930. It isn't clear if the internals also use lesser quality components.
Currently selling on Amazon (Anker's primary distributor) for just $29.99, the TC930 is a viable alternative to pricier options. It pairs, it transmits, the keys stay attached, and beside feeling a little cramped because of the iPad's form factor, I can't provide a functional negative, though it doesn't share the fit and finish of the Logitech Ultrathin. Differences in quality won't show up in short-term reviews, but if you treat your keyboard with the same finesse as your iPad, it is likely to last a good long while.
Good typing feel. Thin and light. Magnetic attachment to iPad. Integrated stand helps stabilize iPad.
Rubber feet aren't integrated (the box comes with two sets) so the keyboard could loose its footing during travel.
This low-priced keyboard offers the same basic design as its slightly pricier rival and performs well in use, though it doesn't match Logitech's details in design or manufacture. That said, it is significantly less expensive, which is a trade-off some may be willing to make.