it may or may not be sold out, so go check.
side note: the official dock needs a Micro HDMI cable and does not come with one. that surprised me quite a bit for an official asus product! thankfully those are cheap enough online.
i'm going to add some general info on my experimentation with the nexus7 and slimport, just to help anyone searching for useful info.
first and foremost: the official dock looks like it's just slimport. not much in additional features. no extra USB ports, no hub.
slimport hardlocks on the latest unofficial 16 build. , but it works just fine on the latest official lineage-14.1-20190208-nightly, and stock 6.0.1. latency is negligible. (0-5ms range)
it appears there is no way to use additional usb peripherals on a microB slimport device (3.0 type C devices can obviously overcome this limitation with ease) so if you're planning a project for your nexus7, make sure all other peripherals are bluetooth.
Qi and NFC still functions in slimport mode. (idea: maybe add an nfc tag to the dock to trigger a custom configuration change when entering docked mode, and add a second one elsewhere for reverting back upon removal)
i am in a position where i can easily test slimport features with the 2013 wifi, so if i missed something, feel free to ask.