Hi Hayden,
1) This being a 3rd party solution, it seems you might have to pay for it.
2) I have not used it personally, so would not be able to give any feedback in this regard.
3) You might want to have a look at the first 2 links that I shared, as it does not involve any costs.
4) Additionally, I would also suggest you go through some videos on youtube regarding "Funnel charts using Excel". for eg, you might be able to create a funnel chart in Xcelsius using Stacked Bar chart.
Hope this helps !
Regards,
Monish