I lived and currently work in holiday rental in the Canarian Islands, the winter season is a very touristy season here. Tbh it is almost all year round but May/June/September are usually the cheapest. Anyway the Canarian Islands are not a good reference, it is reputed to be one of the place in Europe to have the highest rent cost compared to income. Even for long term rental (year or more) it is hard to find anything under 700/800€ without local contacts.