I'd like to hire a carpenter in the SF Bay Area to make a set of
wooden credenzas for our dining room.  Do you have any suggestions for
how to find someone good who will work for a good but not HUGE wage?
We are not in a position to pay more than $500-$750. Thank you!

1.  You're mistaken about what a carpenter does.  Carpenters build
houses not furniture.  You need furniture mfgs.

2.  Next, search Google for "custom furniture SF." I was able to get
what I wanted for the price you posted.

I'm finding some nice custom cabinetry in your area, but so far not a
lot of prices except by email inquiry -- which mamkes sense because
price would depend so much on what style, wood, details, even joinery
methods you require.  However, here are a few nice examples of the
range of what's available to you in San Franciso:

Better Space
http://www.betterspace.net/unique.html
Simple elegance, see that lovely maple credenza!

Tom McFadden
http://www.mcfaddenfurniture.com/gallery.html
This fellow seems like a real craftsman of the kind it's hard to find
these days.

For more of this sort of thing, look at the Yahoo listing at
http://dir.yahoo.com/Regional/U_S__States/California/Metropolitan_Areas/San_Francisco_Bay_Area/Business_and_Shopping/Business_to_Business/Home_and_Garden/Furnishings/Furniture/
(that's a long  URL so you may need to cut-and-paste it into your
browser "location" window instead of just clicking)

Now, given your modest price range,  I've been concentrating on
looking for independent, experienced cabinetmakers and fine carpenters
in your area.  like Ray Cash (
http://pages.sbcglobal.net/raycash/furn.htm ) and postings on Usenet
(nothing useful, yet).
CraigsList for San Francisco does have a lot of jobs/services
postings, which turned up these to start with:
   http://www.craigslist.org/sfo/sfc/sks/6628974.html
and
   http://www.craigslist.org/sfo/sfc/sks/6610944.html

Finally, don't discount a browse through your local "yellow pages"
directory and the classified ads of your local newspaper. If you or
your friends know any interior designers or residential contractors,
ask if there's anyone these professionals like to work with and can
recommend for custom cabinetry work. Is there a college or trade
school that's turning out fine young cabinetmakers who might be
looking for in-class projects?

When you do find your credenza-maker, thoroughly check out his/her
references, of course, and try to see some real-live examples of work
as well as photographs.  Look for strong and stable construction,
close-fitting joints, smooth finishes, good quality hardware, and easy
action on moving parts like drawers and doors. Clip pictures of the
kind of furniture you have in mind, and take measurements. The more
precise you can be in describing what you want, the more likely you
are to get what you had envisioned. And he/she will be able to tell
you, right up front, whether you'll need to go with painted pine or if
polished teak will fit into your budget!