There are many different currencies in the world. In order to ensure consistency, certain style conventions should be used on Wikitravel.
eg: AZN100 in Azerbaijan, not ман 100, 100 AZN nor 100 Azerbaijani New Manat
However, don't knock yourself out "correcting" USD27 to $27 - there is more important work to be done in plunging forward and writing an up-to-date and accurate free Travel Guide!
Like all abbreviations, you may want to consider spelling out the first occurrence in full (with the notation to be used in the rest of the article following immediately afterwards in parentheses), if there is a substantial risk of ambiguity or ignorance.
Write price ranges using a single currency notation and a single dash with no spaces.
Use a period, "." to mark decimals and use a comma,"," to separate thousands groups.
A billion is a thousand million (US style), not a million million (old British style).
When writing about the price of an item in a country, stick to that country's currency. Do not switch between currencies. Doing so causes confusion and frustration. If you only know the price in dollars or euros, go to a currency conversion site and convert the number. Round off amounts appropriately.
In some countries such as Cambodia and much of Africa, the local currency is so weak or unstable that any larger prices (eg: hotel rooms) are quoted and paid for in a foreign currency. If this is the case, follow local conventions and list those prices in the foreign currency.
In some countries such as Myanmar, foreign nationals pay a USD price for some things (hotels, air and train tickets, entrance fees), but in local currency for other things (food, shopping, buses, taxis). In this case, it is best to list the price in the currency that the foreign traveller will use even if it means switching currencies in the body of the page.
If something falls on an international boundary it may be necessary to indicate which currency (or currencies) the vendor is using. If a seat on the next Tunnel Bus to leave Detroit is CAD4.00, say so.
Even when the vast majority of expenses will be paid in local currency, if the inflation rate is high enough that information will become outdated in only two years or less, use the equivalent amount in USD. This should be consistent for all articles pertaining to the country.
Universally known currency notation exceptions
Prices should be listed with the universally known currency notation that travellers will encounter when they arrive at the destination in question. Most currency symbols will usually be prefixed. Travellers should be able to assume that symbols used for multiple currencies (like $ or £ or ¥) apply to the local currency. Unless there is a real risk of ambiguity, do not use the three letter ISO 4217 currency codes like "USD" nor "GBP" if a currency notation is both well established and universally known as in these exceptions:
As in other numerical expressions, use a non-breaking space (
If you write
If the country or article uses multiple currencies, including foreign ones, use the shortest unambiguous form for each. For US dollars, this is USD. For euros, it's €.