Where did the money come from? (and what about Harry's grandparents?)

[dk59us]

No: HPFGUIDX 90553

mrsbrooksathome:
Here's a question that has always nagged at me: In the first book, 
Hagrid tells Harry about his vault and all that good stuff, and on 
numerous occasions throughout the series, Harry having more money 
than Ron is an issue.  Where did the money come from?  I know Lily 
and James supposedly left it for him... But where did they get it?  
And has anyone ever mentioned what they did for a living?  I know 
they were in the OOTP, but as I understand it, that is not exactly a 
paying career? Ideas?

Taryn provides JKR's response from a 2000 AOL live chat:
What did James and Lily Potter do when they were alive?

Well, I can't go into too much detail, because you're going to find
out in future books. But James inherited plenty of money, so he didn't
need a well-paid profession. You'll find out more about both Harry's
parents later. 

http://www.the-leaky-cauldron.org/quickquotes/
articles/2000/1000-livechat-aol.html

Now Eustace_Scrubb:
This subject always gets me wondering what happened to Harry's
grandparents and when (since they are likely sources of inheritance).
 This quote from JKR suggests that one or both of James' parents were
dead by the time of the attack on Godric's Hollow.  (Of course, James'
inheritance could have come from a favorite uncle, a family friend or
an escaped convict lurking in the marshes, but it seems more likely to
have come from his (recently) deceased parents.  I say recently
because (and I only have PS/SS at hand right now) I seem to recall
that Sirius was taken in by James' parents when he left the Black
household late in his Hogwarts career.  If so, that would seem to mean
that both of Harry's paternal grandparents were still living when
James and Sirius were about 16 or 17, but seem to have been dead by
the time the James was 21 or so (his age when LV killed him).  We've
heard about a lot of people who died in those years, but unless I've
missed it, nothing about James' parents...do we even know their first
names?

And what about Lily Evans' parents?  We know little more about
them...maybe less.  We know what Petunia tells Harry and Hagrid in the
hut off the coast:  "But for my mother and father, oh no, it was Lily
this and Lily that, they were proud of having a witch in the family!"
(PS/SS, Chapter 4)  Do we ever hear _anything_ more about them?  

Presumably all four are among the "at least ten others" Harry sees in
the Mirror of Erised (PS/SS, Chapter 12) but we learn only that some
of the figures had green eyes and some had knobbly knees, etc.  Only
James and Lily are described in any detail.

Trying to read clues to the rest of the saga from what JKR _has_
written or said is hard enough, but I can't help feeling that such a
complete _lack_ of mention of these four people must be significant. 
Has JKR ever said that we'd learn more about Harry's grandparents...or
only his parents? 

Eustace_Scrubb