Welcome to the forum.
Firstly, don't get fully focused on low mileage cars. As in your FB post, you said yourself, a 60k car that was abused around the track and not serviced right would be in far worse condition than a car with 100k on the clock which was used as a daily looked after.
My Zed is just over 70k miles, I only do about 4-5k miles per year, but I still service it twice per year and it's been supercharged for nearly 3 years now with zero problems.
Regarding insurance... As said above, try admiral. When I got mine, I actually forgot to do insurance check before I bought it and at the start I was getting over £2k quotes. I went with admiral and it was 1600...I then added my mum as a "named driver" and it went down to 800. So give that a go, unless you already tried it.