This article is from the Theatre FAQ, by aku@leland.Stanford.EDU (Andrew Chia-Tso Ku) with numerous contributions by others.
In this age of instant gratification, people often overlook snail
mail, a slower, but far cheaper means of buying tickets. There is no
service charge involved, and you can request seats in a particular
area of the theatre and for a particular date or range of dates (but
if you are overspecific, you'll get your check returned and a "no can
do" note). I have found that I have always gotten better seats via
mail order than through phone orders, but now that seat locations are
available over the phone, this point may no longer be valid. Some
shows will offer mail orders weeks or months before telephone orders
Payment: By check only. >>> Include a self addressed stamped envelope.
Turnaround: 2-3 weeks, but this is ballpark
Address: You can find the address to send your payment and SASE
in the alphabetical listings in the Sunday New York Times, OR
you can call Telecharge/Ticketmaster (make a note of which
agency your show uses) and they will tell you an address to send
mail orders to.