sure its worth doing yourself.
You may want to also consider looking for any freeze plugs which may be
corroded through if you can't find the leak on the logical suspects. If the
water pump has never been changed, sounds like you wont be wasting your
money by changing it even if its not at fault.

I don't know if this helps, but I had a 90 mustang that had coolant
leaking from the water pump.  I am comparing these, because the mustang
also had the 2.3L 4cyl.  It turned out to be just the seal between the
water pump and the engine that was leaking, but since a new pump was
only $12 and I had to take the old one off to replace the seal, I just
replaced the pump at the same time.  I don't normally do a lot of work
on my cars, but this only took me a half hour and the only tool I
needed was a socket.  This car had 180,000 miles and i was just driving
into the ground to avoid putting too many miles on my new car (I drive
35000 a year!).  I got rid of the car last summer, when the
registration ran up, the engine was still going strong, but the body
was shot.  I just bought a 97 ranger last week to replace it, since it
is a similar engine, I hope it will last me (although it is in the
garage now, but that's another post!)