Magento calendar for renting option

I need to add on an existing Magento webshop an option for renting the products which in the same time are also for sale. Just a simple Javascript calendar where the client can choose 'DATE FROM' and 'DATE TO' for renting the product. After choosing the dates, the script must calculate the price for renting. On the calendar must be also seen teh availability of the product for rent. If other client already booked that product that period of time must appear in red. I don't need a full booking module or so, just an extra option (or attribute) for the products that are already for sale. As simple as possible.