Exchange of money should not be on the black market, but only in authorized exchange offices. The exchange certificates should be repealed, possibly because of the departure is required thereafter. Mostly you get official offices in a very fair price.
Ariary really should not be executed, but the rules are not as strict as in the past.
ATMs are the last state of knowledge (May 2006) only in the capital and also there exists only in a bank. On these machines can be used with VISA Card money separate. This works normally without problems. Who money with Traveler’s checks apart, should its purchase receipts from the same store, because otherwise the banks do not accept traveler’s checks. In smaller towns, the withdrawals of money – even with VISA or Amex card – may be difficult, so you should always be a larger amount of cash (preferably in Euros) to have it Swap. Other currencies (including dollars or Swiss Francs) are often not accepted.
On the local markets (especially in the souvenir purchase) is acting normal, but it should not be exaggerated. The goods are normally already relatively cheap and you have the population does not yet anyway addition to the already meager wages bring. Quite to the action but refrain is not good, because otherwise the prices might soon could explode.