I priced out all the parts that they list on Amazon (and a mid-grade PSU since I didnt see what they use for GPUs) and it comes out to just shy of 1300 USD.

You can probably actually get it cheaper than Amazon from many local retailers, or from NCIX in Canada and the US, but I wanted to use something globally.

So 1300 USD .... for the computer they charge 3200 GBP for.  At a current exchange rate according to XE, thats 974.38GBP   Literally greater than a 3x markup.

I get it, people need to make money, assembling computers takes time, but not 2200$ worth of time.