Tours to Madagascar in October are gradually losing their popularity. You can still ride catamarans, enjoy yachts, especially in the northern part of the country. There are quite a few sheltered coves and bays. Divers love the vicinity of the islands of Nosy-Bi or Nosy-Burahi (Ile St. Marie). In the south-east of the country there are also many villages that offer not the most expensive vacations.
In general, for some time the rest in Madagascar in the fall becomes more of an excursion. At least, until the rains fall. Although there are no pronounced wet seasons, in late fall and winter rains are much more frequent. You can go to Antananarivo, the civilized capital is good at any time of the year.
Prices for vacations in Madagascar in October are already much lower. It is early to talk about the complete decline of the season. Especially if you book tickets and accommodation a few months before the trip, you can save money. The average price for tours to Madagascar in October will be about 2000-2200 USD for one with flight and accommodation.
If you don't know which cities and resorts you can go to for your budget, use the tripmydream service. It will find the most profitable tours to Madagascar in fall.