It is possible to aquire cheap airline vouchers if you
know why the airlines issue them and where the best
opportunities of aquiring them are.
Not only is it possible to go cheap but it is also possible to go free.

Airlines have realized that a certain number of customers
will be no shows…get sick,flat tire on way to airport,
changed thier mind, etc and to prevent a loss they overbook
the seats to make up for the no-shows. Its a form of insurance for
them. As a rule they will have a tendency to overbook
more on the morning flights because they can then issue
vouchers for later flights in the day.
Other reasons for issuing vouchers would be other airlines
delays or cancelations which can mulitply as they try to
rebook passengers from other flights, weather, etc,

If more show up than seats on the flight the airline has
to make a decision on who will get bumped. They will ask
for volunteers unless they have enough who have already volunteered.
The only way they can get volunteers is to give them
something of value. A voucher or free round trip tickets at
a later date usually is enough of an incentive.

Being respectfull and polite will go along way in getting
the best possible voucher. Other things to remember is
to keep your checked baggage to a minunum and being flexable
with your time. Leaving a day earlier than any
scheduled activity would be a good idea.

Cheap airline vouchers are possible with a
little planning and patience and luck.