The search I am think about is just to identify which property is showing available for a certain date. I would think this would be a valuable tool that your competitors do not offer. Using your words "available calendar" means what is available? You allow for multiple calendars so why not with those calendars check to see what is available.
Here is what I envision:
The basic calendar page has added a search field on top with a date range and mini calendar pop up to select 2 dates (start & end) and a select button. The result is a new calendar that was found. Now for me an important requirement would be in the admin page, you get to select the output of the result of a new calendar or a link that I would set. This would allow me to show the available property with it's calendar.
One more piece that make this great. On my main page where I have multiple properties listed with a brief description I would like to put a date range search box only. So the same search process takes place. The script would be the same, output the same but I would need the HTML code for only the search box etc.
Visit my web site to see how I have set up your calendar and how I would use this search feature.
http://basslakeca.com/marcslistings.htmlSo if you took on this project what would you charge me? Of course this could be a add-on to you free script, for a small fee have this extra feature. My email to discuss off the forum
ms@basslakeca.com