JARVIS plays a lot of online gambling type games and being a computer he wins every time. Unbeknownst to even Tony, JARVIS has saved up a hefty little nest egg this way, despite it being unlikely that a computer would ever need his own money.
According to the novelization, Jarvis does have his own money (or at least an access to one of Tony’s accounts, considering the fact that it would be rather difficult for him to have an account in his own name):
[Tony] turned back over the Unisphere, watching to see if it was going to fall over. He didn’t want it to, but it had just absorbed a whole lot of impact energy that it wasn’t designed to absorb. (…)
“Unisphere appears intact and rotationally stable,” Jarvis reported.
“Who cares about the Unisphere?” Tony snapped, irritated that Jarvis had seen through him so easily. “Figure out Rhodey’s OS. What do I pay you for?” (Iron Man 2 by A.Irvine)
On an unrelated note, it’s adorable how Tony tries to convince everybody (and himself) that he’s not a sentimental person. When it comes to the things he (or his father) created, he’s a walking definition of sentimentality.