Yes, the k3 can be purchased assembled.
The kit is a "solderless" kit.  I gather this means all the boards are prebuilt, all that needs done is assembly.
I have ordered the ten watt kit version.  It is supposed to be delivered in November, and I will report on it when it arrives.
I will be working with elecraft to develop blind friendly instructions for putting the kit together, and also helping with the accessibility firmware for the rig itself.
I'll keep you all posted as I learn things.