https://support.apple.com/mac/repair/service
MacBook Pro Out of Warranty
16-inch MacBook Pro $199
15-inch MacBook Pro with Retina display $199
13-inch MacBook Pro with Retina display $199
15-inch MacBook Pro $129
13-inch MacBook Pro $129
17-inch MacBook Pro (Vintage) $179
MacBook Air Out of Warranty
13-inch MacBook Air $129
11-inch MacBook Air $129
MacBook Out of Warranty
12-inch MacBook $199I'm not in the US either.
Where I live Apple offers the same fixed-price battery replacement service but in local currency.
But if I go to a non-Apple store, but an "approved seller" of Apple products, they will quote a much higher price. I challenged them about this once, and they said it wouldn't be cheaper anywhere else, so I showed them the Apple page and they admitted that was much cheaper and I should go to the Apple store.
I told you about the Apple service in case you were being ripped off and would appreciate knowing about the Apple fixed price service, if you are in a country where they do that.
US $ prices were provided because you quoted $800, presumably US $. Other country prices are on the Apple website with a bit of searching. Look up battery service.
Refund method was asked for, which is rather dependent on country. If you're in a less-likely-for-HN country and asking how to get a refund it would make sense to say which country.
People are still recommending second hand 2015 rMBPs as the "last good" ones. It would be a pity if they can't have batteries replaced.
[1] https://www.macrumors.com/2017/05/20/apple-ends-2011-macbook... [2] https://support.apple.com/exchange_repair
All of this in North Macedonia, with no Apple stores (but the fix was done at an authorized reseller). To be honest I was kind of amazed they did that and definitely left a lasting good impression of them.