CMS/Database query/apartment rental

I run an apartment rental business with 35 odd apartments on the books, but upwards of 100 shortly. I am looking for a simple on-line search for availability - plus price calculation. The pricing calculation matrix is simple - will develop more later.

The system requires a simple search box (date in, out, days, num of people) and the resulting available apartments displayed back in a relatively simple form.

There are multiple log-ins required for blocking dates on certain apartments, requiring up to 3 levels (super log-in, agent specific log-in to multiple apartments, apartment specific log-in)

This will be phase one of a 6-7 phase project developing over the next 3-6 months.

Not looking for a specific price at first contact - budget is dependant on me sending a more precise set of requirements. Will be very content to have an example of previous work or secure knowledge of the developers ability.