With orders of $25 or more, Amazon offers Prime members the Crayola Fabric Crayons 8-Pack, model no. 52-5009, for 98 cents with free shipping. (Non-members can spend $35 to bag free shipping.) That's the lowest total price we could find by $5. These permanent colors can be heat set with a dryer or iron.
Note that this item is part of Amazon's "Add-on program" and can only be purchased with an order of $25 or more.