Like this listing does, most listings indicate the distance of the rental from the rail station or other transport stop. There's also a link to the owner's private website, which in this case lists the same prices, but also indicates that discounts are negotiable for long-term stays (more than 6 nights.) Such discounts are very common when you book directly with the owners - sometimes with just 4-5 night stays. In your situation, I would ask about a long-term stay discount in every inquiry.