HEY GUYS! STOP PANICKING FOR A MINUTE!
Now before you start charging off to 'rescue' this goat, use a bit of common sense.
Yes, the doe is skinny. But is she milking? Its not uncommon for really high producing does to look like that - nothing much you can do about it. From these pics she doesnt look like she's milking, but then again there is always the possibility that the photos were taken right after she was milked out.
Now the second, more important thing is, the ad says 'healthy' but I would be extremely suspicious that there is an underlying health issue responsible for the emaciation. You go charging off there with $50, buy the doe, take her home, turn her in with your existing goats/sheep/cows/horses/chickens, figure you'll give her a heap of love and food and she'll be alright. Chances are this doe is chock full of worms and lice, which combined can drag them down awfully, and you just introduced that to your herd. Even worse - I would be highly suspicious that the doe is infected with Johnes disease - prevalent in dairy animals of all species, and causes emaciation even if they are getting enough fod. Now lice and worms you can deal with, Johnes is untreatable, incurable, and they shed the organism in their faeces and it is HIGHLY infective, so basically if you bring one infected animal onto your property, you are pretty much guarranteed that the rest of your flock is infected. And its not just restricted to goats - sheep and cattle get it also. Johnes is a death sentence - it remains viable in your soil for many many years, and vaccination isnt 100% effective so there is NO eradicating it once you've got it, unless you euthanase all the animals on the property, destock and do not restock for 5 - 7 years, or begin fresh on another property.
I strongly urge you to proceed cautiously in rescuing this animal; please only do it if you can secure a trustworthy record of her history, AND you have a very good quarrantine area set up.
I am not against rescuing livestock; on the contrary I do ALOT of caprine rescue. But I do a lot of leg work checking into the history of the animals, and I have an EXCELLENT quarrantine station to protect my herd. If you cant be sure that she is safe to introduce - then dont get her. I passed up on rescuing a 4 yr old british alpine girl just recently, even more emaciated than the photos of this one, because she was at high risk of Johnes infection.
Oh another thing to add is dont believe the age of her ... check her teeth yourself. Alot of rescues come to me 10yrs+, with no front teeth left, those does are physically unable to eat grass so are faced with a lifetime of handfeeding, grain and hay ... ask yourself if you are prepared to make that committment.