If you must have excel, I

[an]

If you must have excel, I like this template the most:
http://office.microsoft.com/en-us/templates/results.aspx?qu=amortization&ex=1&origin=TC001056620#ai:TC010073881|

I actually modified this one to also calculate tax saving as well, based on my own tax bracket. Within this one, it’ll show you how much you have left on your loan after each month. You then can just subtract that from your estimated price and yield your equity.