why is the Valve Index so much more expensive then all the other VR kits?...is it worth it?
No, I do not believe its worth it. The hardware is ahead of its time in terms of resolution/refresh rate, foveated viewing might have made the thing worth it, or if it even somehow supported SLI/GPU per screen. But current hardware is not going to fully utilize that thing and at $1K... I took a pass and moved from HTC to Rift S.
I think the Rift S/Quest w/ Oculus Link/Wireless streaming is worth it. I would lean more towards the Quest for portability if you travel a lot (nice to have one's own personal theater).