So I bought a EVGA 3080 12G 12G-P5-4879-KL, thinking it was a 12G-P5-4878-KL. I did not realize it until I prepared to install it. The main differences is the 4878 comes with the cooling fans, pump, hoses, etc. The 4879 is just the water block. 
Customer Service says sorry, but EVGA can no longer supply the missing parts, can not exchange the cards (listed as the same price on this site), or advise. I did find a 3rd party selling the EVGA 400-HY-1978-B1 conversion kit for the XCS for $185 US (it is no longer available on this site, even as B-stock).
That includes the missing parts, but since it is a sealed system, it appears I would have to replace water block anyway?
Anyone know of a better system upgrade? 
If so, please be fairly specific, I'm new at this water stuff...

sixfive442
So I bought a EVGA 3080 12G 12G-P5-4879-KL, thinking it was a 12G-P5-4878-KL. I did not realize it until I prepared to install it. The main differences is the 4878 comes with the cooling fans, pump, hoses, etc. The 4879 is just the water block. 
Customer Service says sorry, but EVGA can no longer supply the missing parts, can not exchange the cards (listed as the same price on this site), or advise. I did find a 3rd party selling the EVGA 400-HY-1978-B1 conversion kit for the XCS for $185 US (it is no longer available on this site, even as B-stock).
That includes the missing parts, but since it is a sealed system, it appears I would have to replace water block anyway?
Anyone know of a better system upgrade? 
If so, please be fairly specific, I'm new at this water stuff...

According to EVGA's product page, the 400-HY-1978-B1 kit doesn't work with the 12G-P5-4879-KL GPU.  The 12G-P5-4879-KL is a FTW3 series GPU and that hybrid kit is for XC3 GPUs.  You would need to get either a FTW3 compatible hybrid kit or build a cooling loop.
 
You aren't the first person who purchased a hydro copper card by mistake.  What computer case do you have?  Would you be willing to build an open loop?  Your other option is to sell the card and buy a different graphics card.

Watercooling is a large upfront cost investment, especially if you do it right. It also takes some time to learn and figure out. I am very much an advocate for watercooling, but it's not for everyone. If you prefer to stick with air cooling the 15% restocking fee route might be your fastest, best option. That being said, another option is you can always try trade sites like https://www.reddit.com/r/hardwareswap/ where people will swap computer hardware for what they specifically wanted. You might even be able to trade it to your advantage there, but it's always an issue of timing and how long you want to wait. 

sixfive442
Thanks for the "You aren't the first person..." comment. Googled around, and several comments noted I could just buy the (sold by a third party) XC3 kit, two connectors, some extra coolant, and cut off the water block (thereby voiding the warranty). 
 
And a drill and some screws to mount the pump/fan unit on the card. 

you could do that, but honestly, doing that just to use an inferior AIO cooling kit makes zero sense in incremental $ spend and in time/materials plus loss of warranty
 
just get a pump/res combo, some EDPM tubing, 4 fittings, some koolance 702 coolant, plug it all in and you're done.
 
if you post some pics of your rig, it would be easier to recommend options.

hey Six,  youtuber is correct, mixing metals is bad.  post a pic of your rig, lets lay it out.  then you can decide the path.  others might chime in too.
 
you're right you need a rad and fans.  I assumed you had fans already in your case, which you would reuse.  either way you would need fans, whether AIO or custom loop.
 
 

I agree. I took a long look at the Antec case, and while it has two 120 mm fans at the top, a radiator would impinge on the motherboard. I did find a pump with a square radiator (Corsair) which would fit inside the case, but that would still leave me with a small radiator and sticking out of the top. And far away from the fan slot on the video card.
 
After much research, I have determined I am incapable of telling a good loop from a crappy one. Any loop/case recommendations?