As a hotel owner our prices vary all the time depending on demand it’s supply and demand if the rooms are empty it’s better to sell them at a lower price than to have them sitting empty similarly if there’s high demand prices will be higher. Pre paid reservations with a deposit can cancel rooms booked for a lower rate if they become available but they loose ...
Note that the following is based on random web searches and not based in any first hand experience:
From an answer on this 6 year old thread on Trip Advisor:
... you can't buy rufiyaas outside Maldives, and you can't sell
You don't need rufiyaas at a local island either, it's enough with
This Holidify website says something ...
Credit cards usually exchange at bad rates, so I'd recommend either Revolut card, or exchange cash in "Kantor". Great majority of "kantors" (exchange offices) don't take any commision and rates are competitive- much better than at banks.