How to approach creating an interactive web tool / widget?

A very begginer question here as I don't really know where to start. I've done some googling but I'm not sure I'm using the right terms. It would be great if someone could point me in the right direction.

I would like to create a web tool (widget?) like this bbc tool, where you can enter information and have results returned. Mine would display who could afford to rent in a geographic area - with the inputs including the area to dispaly, the income level and a few other variables. Ideally it would be designed so it can be 'inserted' into existing web pages, news articles etc.

I've got the tool setup in excel to test the concept.I'm just not sure of the best way to turn this into an online tool. Do you have any suggestions on the best ways to approach this? If I want someone to do it for me, what type of web developer should I contact and what rough cost would I be looking at?

Thanks