Now we reach the nobility of Renaissance Italy, not at all any aristocracy
but rather the rich and powerful - wealthy merchants, bankers, manufacturers,
patricians etc, the Popolo grasso which - in order to be eligible to vote -
all were assembled in the Arti Maggiori, the big guilds.
The 'natural' aristocracy had already been deprived of their voting rights at the end of the 13. century, leaving them no other chance than to list in the big guilds themself in order to restore at least a fraction of their former power when Italy just belonged to bankers and merchants. Of course people were still impressed with titles and nobility so lucky were those who had both a noble birth and a noble purse. However the latter could easily make up for the lack of the former but this wasn't possible the other way round.
One most popular example for nobility born from wealth would be the Medici family, once wool traders from the rural Mugrello area north of Florence they rose to one of the richest and most influental families of all Europe, bringing forth three popes and numerous rulers of Florence, their family owned Medici bank being the biggest bank in Europe.