Most paper money dealers don't have stores in the same sense as
coin dealers.  Most transactions occur through the mail and over the
phone.  It may seem less than ideal initially, but it works very
well.  Nearly every dealer who works through the mail offers a
money-back, no-questions-asked policy.  If the note you buy is not
really the one you want, you can almost always return it.

  Typically, collectors will use an adequate reference book to find
the note they want.  Then, they look through the many price lists they
might have to find a dealer who offers the same note in an acceptable
condition for an acceptable price.  Lots of dealers put parts of their
price lists in Bank Note Reporter ads.  The collector then either calls
or faxes the dealer with a credit card number or send a check in the
mail.

  The next most typical transaction occurs at paper money and coin
shows.  Often dealers will offer discounts at shows, but usually
only when you buy enough stuff.  It's all fairly informal really.
Shows are also a good way to learn about notes and the hobby in general.

  Another type of transaction is where a collector sends notes to
a dealer who may then buy them or return them.  It's best to ask
the dealer first with the list of notes you plan to send.  This
is an acceptable and safe way to do business as long as the dealer
is reputable (membership in PCDA or IBNS is a good reference as
dealers can and do get thrown out for violations).

  Yet another type of transaction is the mail auction where collectors
all put up their notes for auction (usually through the mail) and
then a list of notes is sent out to a large group of people who bid
on the notes through the mail.  Thousands of notes are auctioned this
way.  The IBNS has regular auctions with about 2000 lots per auction
and minimum bids starting at 2 US dollars per lot: clearly an auction
for regular collectors.

  A less typical transaction is where people place ads in Bank Note
Reporter or the IBNS Journal or elsewhere asking to buy/sell/trade
a specific set of notes.

  The really expensive stuff (1,000 to 50,000 US dollars) is usually
sold at large auction houses such as Spinks (the coin and currency arm
of Christies), Stacks and some paper money specific houses (Currency
Auctions of America and Lyn Knight Auctions).  They also handle lots in
the 300 US dollar range and above.

  And of course, there are cases where people advertise things like,
"Bolivian citizen looking to trade Bolivian notes for Canadian notes"
in *relevant* publications.

  When buying notes, avoid notes that have been cleaned, patched, 
ironed or otherwise "fixed up" to improve the looks.

Be careful of notes which have missing details, serial number digits,
etc. They may have been removed with an electric eraser.