How much do you want for it?

Seth, I have a contact who has several cobraheads that are dead (some still work), but they are $40.00 each.  If you are truly interested, let me know the exact specs for cobrahead you are looking for, and I will find out if he has any.  You would be responsible for any restoration work.  They are in pretty junkyard shape.  I had Mike McCann of McCann Lighting restore my GE M-250R1 for a good price.  Once I find the light, I can ship it to you (35-50$ shipping), and you can either restore it yourself, or possibly see if he will take the job for you for the right price.  He did a damn fine job of taking my rusty old M-250R1 and making it look like a brand new 250W HPS M-250R1 (Since GE doesn't make MV anymore).  You could always get a MH ballast though.
https://www.ebay.com/itm/NEW-GE-GEM175ML5AA3-5-Metal-Halide-Ballast-63078-Free-Shipping/263215317047?epid=1860046592&hash=item3d48db0037:g:-ooAAOSw1KNZv-3J

I sent Mike the light and all necessary parts, and he did a professional job, and I recommend him and his services to anyone.  But I would contact him first and ask if he would be interested in taking the job, as he is also busy. 

Seth, I have a contact who has several cobraheads that are dead (some still work), but they are $40.00 each.  If you are truly interested, let me know the exact specs for cobrahead you are looking for, and I will find out if he has any.  You would be responsible for any restoration work.  They are in pretty junkyard shape.  I had Mike McCann of McCann Lighting restore my GE M-250R1 for a good price.  Once I find the light, I can ship it to you (35-50$ shipping), and you can either restore it yourself, or possibly see if he will take the job for you for the right price.  He did a (...) fine job of taking my rusty old M-250R1 and making it look like a brand new 250W HPS M-250R1 (Since GE doesn't make MV anymore).  You could always get a MH ballast though.
https://www.ebay.com/itm/NEW-GE-GEM175ML5AA3-5-Metal-Halide-Ballast-63078-Free-Shipping/263215317047?epid=1860046592&hash=item3d48db0037:g:-ooAAOSw1KNZv-3J

I sent Mike the light and all necessary parts, and he did a professional job, and I recommend him and his services to anyone.  But I would contact him first and ask if he would be interested in taking the job, as he is also busy. 

If he wants a new MH cobrahead, he could just get a 115 instead and get 70 or 175w PSMH, disconnect the ignitor, and use a merc in it.

I am looking for a mercury vapor fixture  that is eirther 100 or 175 watts. I prefer to have an enclosed fixture such as a cobra head, a wallpack, or a floodlight. Does anyone have a fixture that they want to get rid of?

Check eBay. I just bought a Holophane wallpack 100W H38 120V. (I converted it to 70W HPS...will eventually sell the MV ballast.)