If you like it, here are two websites would do it for you -
It works with more than 15 retailers as well as all Citibank credit cards and all Mastercards (for up to 4 claims per year). It will deduct 25% fee from each refund, or you can pay $9.99 for a monthly subscription. If you link credit card accounts that offer price protection, you can also get refunds on purchases from Amazon.com.
It's a Capital One company, it will monitor your inbox for receipts from more than 25 major retailers, but it does not monitor your credit card accounts.