The printing press was invented and the first Bible printed in 1454, 29 years before Luther was even born in 1483 and 66 years before Luther broke with the Church. bl.uk/treasures/gutenberg/homepage.html
The problem was that illiteracy was high at the time, only the nobility, some of the merchant class and the clergy could read, so even if people could now get hold of a bible, most still couldn’t read it. Luther was a monk, therefore, part of the literate crowd.
The idea of indulgences being sold is a misunderstanding of the indulgence granted for almsgiving. Alsmgiving, or donations to the Church for such purposes as building new houses of worship which benefit the entire faith community were enriched with indulgences. Others have gone over just what indulgences are, ie - not the forgiveness of sins but the remission of the temporal punishment due for sins already forgiven. Almsgiving has always been a major tenet of Christianity and of Judaism before it. Unfortunately, since the money was being given to the Church, it took on the appearance of being sold. Moreover, since only those with some spare cash could afford to give alms, it looked like the rich were trying to ‘buy their way out of Purgatory’ while the poor still had to perform the lengthy penances.
As an example, lets say a person committed the sin of blasphemy and was given a penance of 100 days of fasting. The rich person could give alms to the Church and obtain an indulgence of 100 days, thus exempting him from having to fast. The poor person, unable to give such generous alms to the Church would have to do the fasting. The poor person could decline to fast for the required number of days during his lifetime, but then the temporal punishment due for his sin would still remain and would have to be expiated in Purgatory.
So, you can see how it appears that the rich person is buying their way ‘into heaven’ or more accurately, ‘out of Purgatory’ with the blessing of the Church and how this could rapidly become an abuse with the rich believing all they have to do is give some money to the Church and they are good to go and do anything they want, no contrition necessary.
In addition, there was one particular monk, Tetzel, who was accused of selling plenary indulgences to get rich himself.
History presents few characters that have suffered more senseless misrepresentation, even bald caricature, than Tetzel. “Even while he lived stories which contained an element of legend gathered around his name, until at last, in the minds of the uncritical Protestant historians, he became the typical indulgence-monger, upon whom any well-worn anecdote might be fathered” (Beard, “Martin Luther”, London, 1889, 210). For a critical scholarly study which shows him in a proper perspective, he had to wait the researches of our own time, mainly at the hands of Dr. Nicholas Paulus, who is closely followed in this article. In the first place, his teaching regarding the indulgences for the living was correct. The charge that the forgiveness of sins was sold for money regardless of contrition or that absolution for sins to be committed in the future could be purchased is baseless. An indulgence, he writes, can be applied only “to the pains of sin which are confessed and for which there is contrition”. “No one”, he furthermore adds, “secures an indulgence unless he have true contrition”. The confessional letters (confessionalia) could of course be obtained for a mere pecuniary consideration without demanding contrition. But such document did not secure an indulgence. It was simply a permit to select a proper confessor, who only after a contrite confession would absolve from sin and reserved cases, and who possessed at the same time facilities to impart the plenary indulgence (Paulus, “Johann Tetzel”, 103).