Renovate gas heating - costs?

In an 85 m2 apartment, the gas heating system needs to be renovated, the existing one is from the 50s or 60s. The boiler runs somewhat unevenly, the CO value is at the limit, and some radiators are rusted through.

The question is what costs one should expect.
A new boiler is already available for 1000 E, I have estimated the radiators with 8x 300 E, which makes 3,400 E.
But a friend who is a craftsman mentioned "about 10,000 E".
Is the installation really that complicated?
Do the pipes definitely have to be replaced?
They are made of copper and should not wear out, rust, or similar in my amateur assessment - right?

Thanks for the advice / ED

...The question is what costs one has to expect...

Which costs are we talking about? Investment, running costs, or overall profitability over 20...25 years?

...But a friendly craftsman mentioned "about 10,000 €"...

Quite a few "friendships" ended suddenly after the realization of a project ;-) best regards

Just have 2-3 quotes sent to you.... then you'll know how much it costs.

just have 2-3 quotes sent to you.... then you know what it costs.

What, just the investment? ;-)

regards

Derda, "Just have offers sent to you" - ok, then "Go to other forums and drive users away." Euro, of course it is about the investment, as with the other figures I mentioned.

Derda, "Just get some quotes sent to you" - ok, then "Go to other forums and drive users away".

Euro, of course it’s about the investment, just like with the other figures I mentioned.

I’m not driving anyone away.... but how am I supposed to know what it costs for you here?
I moved 20 km from Karlsruhe to the Pfalz. And what can I tell you.... here in the Pfalz they charge almost 50% less for labor.
So there can definitely be a big price difference, which you will only find out by asking companies directly.

Our earthworks were quoted between €15,000 and €25,000. Any question in any forum wouldn’t have helped us.
And since no one knows how your apartment is set up, no one can estimate the effort either.
Generally, you don’t have to replace the pipes, but if, for example, you live in a concrete house, drilling is more complex, requires heavier equipment, and more time. Nothing has been said about the condition of your heating pipes, nor about their age.

Your craftsman is estimating €10,000... what material costs is that based on? Your estimated €3,400 or is he using a more expensive boiler and pricier radiators?

If you ask me, I would roughly guess... without any real basis, a price between €7,000 and €10,000. Just from experience, how long our installers needed. 3 people for 4 full days, including laying all the pipes in a prefab house.