I don’t have any ideas for the top half of the costume, but I think a pair of Weta Legs would do wonders for the lower half.
You do know there are a lot of different breeds of goats.
Your friend should check out the Regretsy forums. Etsy used to have a feature where you describe what you want and people bid on making it, but they have discontinued that. The (mostly) ladies on Regretsy are Etsy crafters. Someone there will know someone who can make you a goat costume.
I am aware, my friend is trying to go for the generic goat look, nothing fancy, just a costume that would convey a general sense of goatness to an average bystander.
You need tanned goat skins not ones for making drums, those are more like rawhide. My guess is a competent taxidermist would be your best bet.
Is he a furry? There’s a lot of furs out there who costume, and a number who makes costumes on commission. Styles can range from realistic to toony.
Why does your friend(heh) need it? We’re dying of curiosity here.
He’s probably just kidding around, so don’t let him get your goat.
Does it need to be flame-retardant?
Does it need special orificial modifications?
From all the various posts, the devil is in the details.

I dunno, what is real enough? You can buy this. There are a surprisingly large number of goat costumes on ebay.
I like that goat costume. The only thing is the creepy half smile, kind of like the one Thel (mom in Family Circus) generally displays at the antics of her melon-heads.
Furries…
Not furries. My friend doesn’t want to look like some cartoon goat. He wants a costume made out of real goat skin with real goat hair and a real goat skull as a sort of helmet. Imagine what a goat-themed member of the band Lordi would look like, thats what my friend is going for.
I must ask. Are we the first people you thought to turn to when your friend said " I need a goat costume"?
I don’t know whether to be honored or disturbed.
Sounds like something out of Time Bandits.
Be careful crossing bridges. You’re likely to attract as many trolls with your costume as with this thread.
You know, Cecil never specified exactly *which *Ignorance should be fought…
ETA: …for a friend.
The only way the original post could have been better is if it included the phrase “he needs it immediately”
Eventually, we need to see photos of the outfit, if you please…