I doubt you can find anything for that price in peak season. Try JORC like Tom said or Jupiter Bay Rentals, just north of the Bluffs, they're one of the few communities that may have something left and allow 30 days. Call them directly or I can email you the listings. Glad to have you in Jupiter!
Susanna Malmgren-Grubb, Coastal Sotheby's Int'l Realty, Jupiter, FL