In my practice, I've never liked folks calling me and just trying to beat me down on price. However, I've had folks who've accomplished practically the same thing by simply being more polite about it. When my wife and I come, we have our favorite two places to stay. But when I go with my buddies, I'll send out a lot of emails to different places, usually asking them what their best price is they can offer. The answer has been different at different times, but it has gotten me good deals.
I think even for the rate you're listing, you might be able to look at some of the lower-price rental houses, and, if they're empty, they may deal. An $80/night rental house might rather take your $40/night than be empty.