Hi Susie, sorry that you are losing your pond. Water temp. in the northern states are dipping down. I don't know what your water temp. is but transferring a fish to a new home at any time is stressful for the fish.
I would find out the buyers thoughts for the pond and if they wish to keep it. If not, look to local koi clubs or friends with ponds. I did a quick search, found Sante Fe Koi and Pond Society. Hope this helps..Craig

Susie, I'm no expert on koi, but I know some cautionary tales about home-buying. Before deciding whether to give away the koi, perhaps check with the buyers (and agents) to be clear about what the buyers think they're getting in the sale. If they expect seven beautiful Koi to come with the house, there could be problems later (even if you gave the fish away to save their lives). These details are often written into the sale contract so it's clear to everyone involved.

You could post them for sale on Craigslist in your area.. I know in my area the koi sell very fast.