It's a beauty and a very rare one too!Nikon Reflex Nikkor 2000mm F 11 – 2000 11 Extremely Long Lens 13L075 | eBay
I would buy a Telescope with adapter for much less. Here is an example for less than $2,500/ with all accessories
Celestron Advanced VX 9.25" f/10 Schmidt-Cassegrain 12046