When researching pricing and popularity of a region, you'll find that for the Maldives, the high season for resort prices basically runs from December and into April, with December and January easily being the busiest months. This is because it's when most Europeans take their winter break. The rest of the year is considered the “low season” for Maldives resorts, even though the Maldives weather is almost exactly the same the whole year round and therefore there is no best month to go to the Maldives in terms of climate.
With that said, you'll find that July and August tend to be the cheapest months for resorts in the Maldives, as it's quite a popular destination for Europeans who take one of those months off. Better still, many resorts offer drastic discounts during the off-season months, so it's very possible to get a water villa for literally half the price you'd pay during the high season.