Sure, why not?

There's also a third option: get cozy with a Republic or a Monarchy somewhere in Italy and get them to just grant you a title.

By 1492, titles had long ceased to mean anything much in Italy. Sure, some people still touted ancient titles ("I am the Count Malaspina! Fear me!") but most people with the means to do so just bought estates and exploited their tenants while dispensing with titles. Venetian Patricians, for example, only acquired titles by intermarrying with ancient aristocratic families in Verona, Vicenza, Padova, and Treviso, and many Venetian Patricians would remain without explicit titles until the Republic came under the thumb of the Austrian Empire at the turn of the 19th century. However, having a title didn't stop Venetian Patricians from buying and developing countryside estates! On the other hand, the Duchy of Milan in this period had a ruling dynasty that modeled themselves on the French Monarchy, and were probably the most enthusiastic title-granters in the late 15th century. Appropriately most members of the ruling milanese Sforza dynasty were granted landed titles and matching estates surrounding Milan, while aristocrats close to the ruling dynasty were also rewarded with landed titles ("You, I like you. Where do you live? Yes, of course, the Corso Magenta, anyone who is anyone lives there, you silly man. Where is your estate? Calvirate? Very well, you are now Count of Calvirate!")

The Papal States and the Kingdom of Naples were also fairly important granters and recognizers of landed titles. Indeed, when Sforza Maria Sforza (yes both his first name and last name were identical) was appointed Milanese ambassador to the court of Naples, the Neapolitan King made him Duke of Bari and granted him the eponymous fief in the far southeast of Italy (this is actually a lot less weird if you consider that typically, ambassadors were people who were already embedded in the place where they were representing their polity of origin). In fact, the Papal States and Kingdom of Naples were places where many aristocrats were able to obtain and exert archaic aristocratic privileges well into the 19th century.

There are countless anecdotal stories tied to what aristocratic titles and aristocratic privileges meant to various people in various places. Just to cite another example, in 1521 the Papal general Giovanni de' Medici had a sort of nervous breakdown when his uncle Pope Leo died and over the course of the following year dedicated himself entirely to defending his half-sister's fief near Parma from mischievous usurpers (you can read all about Giovanni's life here). While large and small investitures (and ensuing intrigue) of this kind were common in Central Italy, they were only reserved for the greatest of aristocrats across the river Po, in the North of Italy (this in spite of the Sforza's enthusiastic title-granting at the end of the 15th century). In short, the mechanics of obtaining a title either by intrigue or via exchange of money would vary depending who, precisely, was granting and/or recognizing that title. In 1492 (the year citied) there were nearly a dozen polities that could have conceivably granted titles in Italy. Each would be subject to its own internal dynamics, traditions, and institutions which would dictate when and how titles were dispensed.

If, on the other hand, you are asking how someone could come to outright rule a state in Renaissance Italy, it would take much more than money. A legitimate claim to rule, the right connections, and popular support would all be vital in orchestrating a bid for usurpation. Al three of these factors were, just to cite another example, exploited by Ludovico Sforza when he deposed his nephew Gian Galeazzo, and you can read all about that ordeal here.

Unfortunately, I fear this answer might be unsatisfactory to you. Italy was a strange and fragmented place in the period you are asking about, and it is difficult to offer a definitive answer to your question.