Yes, it would go on line 21 of your 1040 as "Other Income".
If you are planning on continuing shopping you may want to go on and establish a Schedule C business, though if your records are spotty you may want to leave that for 2012 taxes.
Not all companies keep your payment records on line or on line for very long after you have performed the shop. In some of those cases your payment may include both your fee and reimbursement, so spend some time and try to figure it out so that you are neither cheating yourself or the government because reimbursements are not taxable.