I’m not sure where you saw that as it appears to be $44.99 + shipping when I look. The tool kit looks nice too! But I already have most if not all of those from various other repairs over the years.
Probably not all that different to buying from your local shopping centre repair guy, although maybe they are buying better batteries to ensure customer satisfaction vs return rates.
In the end I bought plenty of after market batteries off eBay before In the end I went with the cheap eBay option, although only a standard capacity battery with included tool set.
I picked a seller that said they were in Australia and had decent reviews (lots of sellers seemed to have feedback about items that just never arrived). I ordered it on Wednesday night and it turned up on Friday, which was damn quick. Install was relatively straight forward although I had to pull out the heat bag after the adhesive strips failed to pull out cleanly (or at all). I can see why people would pay someone else to do this job.
It’s back together and appears to be working as expected, I have to wait for the official feedback from my son on how improved battery life is!