A small Windows Application written in C# will easily accomplish what you are describing. Unless you want to hide the fact that you are getting the data from another website, I would suggest using an embedded webbrowser control and letting the user actually make the search choices using the same web interface they are used to. Then when the page with the listings of each property it would automatically prompt the user to save these results to an Excel Spreadsheet. The software would then get all the information from the website, going to the details page for each client and scraping that also. The data will then be saved to the Excel Spreadsheet of the users choice, and to the Tab of the users choice.
If however, you would prefer to just have a normal Windows Form to enter the search options, that is doable too, but it would look a little more plain, in my opinion, than the other.
I can do this for you in three days, no problem. I'll remain available for chat for the duration of the project, and will give you periodic updates on the progress of the project. You will receive fully documented source code as well as the compiled executables.
I hope to hear from you soon!
Houston