Vietnamese lady on Cleveland just north of Morse, she does awesome work.
Edit: It's a small shop and you'll know it if you head that direction. Just realized how vague I was. If interested, let me know and I may find more info.
If they don't want to give a discount on 30 gallons, they shouldn't offer it. If I buy 10 gallons and Hick McPickup can take full advantage, is he scamming the system? No. It shouldn't matter.
Write check in the airport for refundable ticket. Accept airport receipt. Go home, cancel ticket, book new ticket using miles. Turn in receipt for full reimbursement. Profit.