Rentalot is free, with no restrictions on its use. It includes the full back end administration interface, and the front end of the component can display availability tables on your site. The plugin allows you to place availability tables anywhere in any article.

Rentalot for Joomla 2.5 and 3.x
Rentalot User Guide Version 4.01
Rentalot Component Version 4.03
Rentalot Plugin Version 4.01.03
Rentalot for Joomla 1.5, 1.6 and 1.7

The latest version of Rentalot only supports Joomla 2.5.5 and above. If you use an older version of Joomla you can download this old version of Rentalot. It is no longer being developed but will be available for download until the end of 2014.

Old Rentalot Component Version 3.09
Old Rentalot Plugin Version 3.04