Nobody here can give you any clue at all what the cost to you will be. There was little point in asking. As you said, the relevant thread contains an awful lot, but contains everything that we know. In summary of it, the answer is that every case is very different.
The only way you will get a useful answer is by getting both the desktop survey result, (I assume that is what you have requested), then even if that is high pay up for the full survey which gives you a price that is frequently much lower, but sometimes higher.
As for your calling the VDSL2 maximum observed speed "stupid", no it isn't.
But I accept it clearly shows the Kbps figure, not the Mbps figure stated. That will be because the descriptive text is fixed, and doesn't cater for figures being quoted in Kbps because they are below 1Mbps.
My broadband basic info/help site -
www.robertos.me.uk. Domains, site and mail hosting -
Tsohost.
Connection - AAISP Home::1 80/20. 200GB. Sync 01/10/18 - 72382/13812Kbps @ 600m. BQMs -
IPv4 &
IPv6
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If you never think of anything off the wall, you'll never think of anything original.