Okay, the title really gives away the whole idea. Rather than using a flimsy, disposable, wipe-clean splat mat under our high chair, we opted to vertically cut an old waterproof shower curtain in half. The result is durable and cheap splat mat.
The best feature of a shower curtain splat mat (other than fact it lays pretty flat on the floor and doesn't bunch up) is machine wash-ability. Add a half cup baking soda to the wash load and a couple towels or sweatshirts (for friction), and air dry. Do not use bleach or detergents with bleach.
***This is the independent opinion of Baby Toolkit, (c) 2006-2008.