Oooh... I have an idea of how I might be able to do this for free... unfortunately my consulting services cost a bagillion dollars (just kidding).
Are you familiar with www.IFTTT.com? They connect different systems together via APIs. It allows you to build an If:Then rule called a recipe. My favourite example is 'If my mother sends me a Facebook message then send me a text message to my cell'. My sweet mother always insists on using Facebook as a medium of communication!
You will need to create a free account to see this, but here is an example of someone that is adding receipts from an email to a new row in a spreadsheet: IFTTT / Add receipts & orders to Receipt Spreadsheet by acidtest. It is very close to what you need. I expect your recipe will follow the format of: If email search returns this then add this piece of information to excel.
IFTTT is very user friendly and I tend to think you will be able to build this without any assistance. Having said that, if you do need my help - feel free to call (519 729 5621).
This is my good deed of the day!
Ian