It seems remarkable to see horses that have not won even a bumper fetching six figures.
On the other hand there could already be a good £50k of purchase money and training fees already invested in them (say £25k to purchase as a 3yo plus 18 months pre-training and training fees). So £100k would be roughly equivalent to the cost of getting two horses with reasonable potential to the track, but it's less than 50/50 that either of them will be any good, and then have the durability and luck needed for a good career.
Taken from that perspective these prices (apart from the sales topper) are not quite so boggling. To have a young horse that's already been to the track and shown some talent already puts you in a better position, in my opinion, than somebody with £100k to spend on two untried horses.
That said, early promise in bumpers or points is no guarantee of further success, far from it.