If the Jedi are supposed to live a kind of monastic lifestyle and not own anything, how do they buy goods/services?
Can a Jedi make a profit out of business, maybe?
Leland Chee addressed this in Star Wars Insider #133
Q. Did the Jedi ever get paid for the job they did for the Republic?
Ask Lobot: As described in the novel Rogue Planet, many in the Galaxy lend their resources to support the Jedi, often depositing funds into a joint account in the Galactic Capital Bank. These funds cover the Jedi's operating costs, like maintaining the Jedi Temple and the financing of missions throughout the Galaxy.
As we see in The Phantom Menace, the Jedi often rely on Republic-supplied transportation when acting on missions on the Republic's behalf.
The Jedi are a monastic order. Although some Jedi skirt around the edges of this (Anakin seems to exclusively 'own' R2-D2, for example) the idea of the Jedi collectively running a for-profit business is basically a no-no.
Attachment leads to jealousy, the shadow of greed, that is. - Yoda - AotC
As to where a typical Jedi gets funding to purchase goods and services, they often seem to rely on the kindness of strangers for basic necessities (trusting to the Force to lead them from place to place), by using ships and facilities provided by the Republic, or just accessing the Jedi's own expense accounts for larger purchases.
The majority of this cash would appear to come from the Republic government in the form of payments for their services toward keeping the peace on various planets. It's noted in the Jedi Path Manual that the Jedi consider themselves to be...
... Public servants, after all
And quoting from the old (now non-canon but still pretty solid) HolonetNews website:
JUDICIAL ARCOLOGY, CORUSCANT - The Judicial Department has denied the People's Inquest demands to reveal budgetary information regarding the Jedi order. The People's Inquest, a Coruscant-based lobbying group built around enforcing the accountability of the Jedi order, began the formal petition for information following last week's unveiling of the new Jedi starfighter.
"We, as the tax-payers that subsidize the Judicial Department and the Jedi order have every right to see how those credits are spent. How much is this new fancy toy costing us, the people who are now finding it difficult to clothe and feed our families?" said Inquest leader Thrynka Padaunete through a loud-hailer before a vociferous crowd of supporters gathered at the steps of the Jedi Temple.
Christian monks live a monastic lifestyle by definition, and yet there are examples of extremely wealthy Christian monastic orders.
The Knights Templar were extremely wealthy, running sort of an international banking system, until King Philip the (Un)Fair framed them and had the order abolished.
The Knights Hospitaller ruled their own territories, Rhodes and later Malta, for centuries, and are still considered to be a sovereign power according to international diplomacy, despite not having a sovereign state to rule at the present.
The Teutonic Knights ruled for centuries various territories that are now part or all of at least four modern European nations - that is certainly political power on a national scale.
Dozens of monasteries in Germany were rich and powerful enough to be the territorial rulers of various small states in the Holy Roman empire. The Imperial Abbesses who ruled some of those states held the only political offices that could only be held by women in Europe of that era.
The Benedictine Abby of Cluny in France was so rich that it built around 1100 AD the largest church in Europe until st Peters in Rome was completed about 1600.
Buddhist monasteries in Eastern Asia were also often wealthy and powerful. During some Japanese conflicts some monasteries had armies of warrior monks.
So if someone ever writes a detailed history of the Jedi Order he will have to explain how the Order acquired its wealth - presumably by countless billions of donations by grateful beneficiaries of Jedi justice over thousands of years.
There was a vault underneath the Jedi Temple which served as a bank for the Jedi Order. Yoda and Mace Windu, were the sole Jedi with access to the vault, which contained a massive amount of credits, provided by the Republic Senate.
The credits were to be used for basic needs, like food and clothes, and also funding for missions. Jedi and their Padawans needed permission from the Jedi Council to receive credits. Credits were also given to Padawans, who were expelled from the Order, so they could start anew.
It's unknown what happened to the vault in the Imperial Era.