On Earth what is a fair price for knighthood, or nobility ?

Huh?

There is not one state of knighthood, nor nobility, for all places and times on Earth, so, it varies widely, and often (if not always) is not something one simply buys for a fixed price.

And, what do you think the notion of buying status, has to do with paying off debts?

@Zaku I was being tounge in cheek about goverment debt.

Let’s say that the US government sold Ellon Musk a title of nobility? What would they charge? It wouldn’t come close to paying the government debt, but would help for a time?

What if 1% of millionaires bought in for lesser titles? Would it help prevent the government when it reaches to a unmanageable level?

@all What titles would you like?

What would Ellons title be when he forms a Mars colony?

There is a sovern country that used to be an ex oil platform in 50 miles from British waters that sells tities of nobility. Was on 60 minutes a month or two ago that reported on the new country.

Cheap on Ganymede.

There are some other countries (and web sites) that sell titles. Those are individual answers to your question. It’s often under $100, and mainly shows the buyer is being egotistical and/or silly.

As for Musk, he already sells blue check marks. ;-)

Nobility adds debts, not the other way around.

Usually your first borns hand in marriage