I can't speak for European prices but in Australia we wouldn't drill and case (line) a single shallow water bore for less than $10,000 but if you wanted a few of them near each other, or a bunch of neighbors all wanted them at the same time, that could bring prices down.
Irrespective of the cost to do the actual drilling (typically charged per meter) there's all the fixed costs related to millions of dollars worth of equipment, staff, etc.
Getting to about 100m would run you closer to $20,000 and be about 2 days work.
900m can be reached with a large mostly self contained truck mounted rig, but it's unlikely to be able to be drilled with compressed air so the rig will need mud pits. These can either be swimming pool sized holes dug in the land or be large tanks brought to site. The work area will need to be around 20x20m minimum with clear access for heavy vehicles and no neighbors to complain about the noise (there'll be lots)
There'll be a lot of spoil to be disposed of, it might only be quite narrow but you are digging a hole to 900m deep and it will add up. On a drill pad (area) the size about there wont be space for all of it and it will need to be taken away in trucks. I'm not costing this in my estimate below
The deeper you go the fancier the caseing (liner) of your drill hole needs to be to withstand the forces in the earth, this may end up costing as much as the drilling.
It would be somewhere around $750,000 if my former employer drilled and cased your hole in Australia, and that's only if the ground was favourable. If it was unfavourable ground we'd pass on a job like that - too much risk of things going wrong, taking too long, and costing us money given we would be charging by the meter on completion.
We actually got enquiries in regards to things like this on a semi regular basis from well meaning people who had no idea how tricky it was to do :-)