In Talers, in Ducats, in Ruble, Euro or Dollars?
Anyway I have the opinion, that income is really not easy to compare, as you have to take the cost of living and the standard of life into consideration. Plus, you have to compare the time today with the time back then, which is not easy too. A German teacher might earn Euro 4,000 in a month, an American teacher might earn Dollar 40,000 a year. Firstly these are no true numbers, secondly it is a sample to tell, it's not just that easy. The comparison, for instance, is even harder, as housing is a lot cheaper in the USA, at least it's true for small houses. And gas is cheaper. However, many things are much more expensive as in Germany. Plus there is a difference of course, whether you want to build a home in Munich, or you want to do that "somewhere" in the country. It just doesn't work that way. By numbers, whether it's Talers or Dollars.
In general we can say, that Bach was definitely not rich, nor wealthy. He had a good living as he received the payment from his job plus more income from performing at weddings, anniversaries and funerals. So he had enough money for a good living and he was able to feed his family. This is what is true as for the average person. Back then no status symbols like we have them today existed for the middle class. I am talking of expensive vacation destinations, cars, brand clothes, technical gadgets. There were, you are correct, there were expensive clothes and you could own horses, real estate and houses - but I believe, it's clear what I mean.
Fact is, that Johann Sebastian Bach left Muehlhausen after an unbelievable, many houses destroying blaze, because after that the cost of living became more and more expensive for him and his family. And we know from the letter to his friend from the Lueneburg era, which he wrote so depressed from Leipzig, that the high prices and the high cost of living in Leipzig as well eliminated the full higher payment compared to what he earned in Koethen.