Cost estimate for exterior facilities - price 45,000 € realistic?

I find the offer quite cheap.

Roll turf is IMHO an absolute waste of money and you have to be extremely careful about what you get; based on experience, the seed of roll turf is usually the leftovers. If I were to design my garden again, I would use only proper seed regardless of the price.

5k cistern - the question is more from which roof area it is supplied and how much area is actually irrigated with it. Considering the existing well, I would stick with the 5k. Does the pump really handle the irrigation both in the cistern and in the well? Quite a few people have been disappointed - but if the garden landscaper sells it as a package, he seems to know what he’s doing.

If the price is okay, I would definitely participate. 5000 liters are gone quickly if it doesn't rain for a few weeks.

He once casually mentioned that he calculated 2-3k for it. As I said, it's all a mixed price, so the individual items are hard to calculate.

You should find something here using the search function.

Unfortunately, I didn't find anything using the search function :/

Roughly estimated, if the garden really needs water, I use about 1k per day. If watering has been neglected and/or I am away afterwards, sometimes 2k, but then everything is dripping. Now my cistern holds 10k and through the large roof area, I get about 5k from a heavy summer rain. So the 10k is enough for me for two weeks if there is a heavy rain in between. With a 260m² garden, the cistern has never been empty during normal operation since we have lived there. Of course, more capacity is always better – but the utilization of the additional 5k is naturally worse because the peaks you cover with it become fewer and fewer. For me, the deciding factor was that the 6k cistern would have cost almost as much as the 10k, but with 10k I received a significantly higher subsidy from the municipality => the 10k cistern was cheaper for me than the 6k and therefore amortized much faster. Keep in mind that a dry cistern pump may need to be flooded again before putting it into operation. Better ask your gardener what he says about the topic of [Domverlängerung], whether it is to access the pump or to remove sediment every few years.

Take a look at the thread "Baukosten gehen aktuell durch die Decke", post no.: 10.479

Does a well make sense on an approximately 1000sqm ? We already have a cistern, 5000l, I’m not sure how the two work together (well, the well then when the cistern is empty, that much is clear).

It depends less on the size and more on how you design and manage the garden. When I read about turf and an irrigation system, it tends more towards the scenario that you use 20l/sqm every week.

Does a well make sense on a plot of about 1000 sqm? We already have a cistern, 5000l, I'm not clear on how the two work together (well, okay, well when the cistern is empty, that is clear).

A well definitely makes sense for the size of the property. When it is dry and warm, your cistern will be empty in 1 to 2 days, if you are very economical, it might last 5 days. This year we already had a few weeks in a row without rain. Then the cistern stays empty.