When thinking about the reimbursements, try to think about the shop and then something you need anyway that you could pick up there. At an office supply store you could get paper, pens, tape, notebooks, folders, etc. Most hardware and home improvement stores carry cleaning supplies and light bulbs. Many stores will carry paper towels and toilet paper.
It may initially cost slightly more than the store you regularly shop, but with getting them reimbursed you are either getting them free or at a reduced price.
I did a shop that was bonused to $25 with a reimbursement for $14 at a store geared toward teens. I took in my daughter who just headed off for college as it was a requirement to have someone try something on. We had planned on buying a few pair of underwear, so she didn't have to do laundry so much, but when we walked in the door their jeans were BOGO. So my fashion conscious daughter got two pair of jeans for just under $44. When thinking about my pay and reimbursement, we got two nice pair of jeans for $5. Had I not done the shop, I would have been out quite a bit more.