I just switched from gravel to Black Diamond Blasting Sand, medium grit, and am quite pleased with the look. A 50 lb bag is $7.99 Tractor Supply Company. Still need to aquascape, but I think the black sand looks pretty cool. Here's a pic:

Looks very similar to to the CaribSea Tahitian Moon... And it looks like you and I have the same digital thermometer!
.The black sand (IMO) brings out the best color in fishes.
That little digital thermometer is dirt cheap on Amazon. I'm going to be buying a few more.