Quick question on purchasing sand vs. gravel?

[laughing]

I have a 20 gallon "community" tank that currently houses 5 balloon mollies and 1 GlowFish, but will have 2 more Glows in the future. (Stopping at that!) Right now they have a *teeny* bit of gravel, so small it barely covers the bottom of the tank! That gravel fills the bottom of my 5, 7 whatever gallon it is tank completely. In fact it was purchased for that in the first place.

I want to do sand with my bettas, and it's easily to get 1lb of aquarium sand for $5, but a 50lb bag of play sand is only $5 too! Aquarium sand I can get in all different colors, say I want to do a "lava" them I can easily get black sand, lava rock, and a cool plant and be done. I wouldn't have anything left over. But if I get the play sand ALL my tanks will have the same exact tan color. I mean, it's not bad, I can still personalize the bowls/tanks with other things, but I won't be able to choose the color of sand I would like to contrast that specific betta's coloring.

So my question is, should I just opt the cheap way and just get the tan play sand, or just spend more money and pay $5-$10 a tank/bowl to completely personalize their habitats?

(On a side note, I do know that if I get play sand I will have to rinse it REALLY well and this can take quite some time.)