Dhaalu is an atoll in the southern sector of Maldivian archipelago. There are mostly good private resorts with great value for money. As for the local islands, beaches are rather mediocre, so it is best to take private tours to uninhabited islets and sandbanks. Shore and seabed: sand, stones. 
Room on a luxury island resort starts from as low as US$300 per night. While room in the local guesthouse is about US$60-80 for a couple. You should always consider all possible accommodation options, as new hotels usually offer great discounts.
Fly to Maldives international airport (MLE). Next take 45-minutes flight by a seaplane (US$500-700 for the round trip), or take a domestic flight to Dhaalu Airport (DDD), or get by public speedboat (4-5 hours per way).