I agree with Bill Maguire that use of an electronic tuner can be
quite satisfactory for the do-it-yourselfer.  I was quite happy with
my results using a Korg and, while a professional would no doubt do
a better job, I'm not sure I could tell the difference (on an old
upright).  With tuning costing around $100 a pop, it's pretty easy
to make a case for buying one of these as long as you have the time
to do it.

Mike Concordia