Looking for an add-on

[Entbark]

I am looking for an add-on to keep track of a few things:

* Who buys my items
* If the buyer is a repeat-buyer
* Which items were bought
* When the items were bought
* If I have sent the buyer a thank-you letter
* Which complimentary gift I sent the buyer with the thank-you letter

Anyone know of an add-on with this functionality? Or would it be easy to make? If it would be easy to make, any ideas where I could start? Thanks!