Careful on using play sand... it can be very high in silicates, which can lead to awful diatom issues. I know several have used it and worked well, but many have also tried it and had issues. It is probably just dependent up what the makeup is of the particular sand you happen to get.
If you want cheap sand, I would look into pool filter sand (PFS). A lot of folks use it, it is not expensive (in comparison to aquarium specific substrates) and it does not contain silicates. It is also much cleaner than play sand, so it will settle out much more quickly, and won't leave much floating in the water.
If you want cheap sand, I would look into pool filter sand (PFS). A lot of folks use it, it is not expensive (in comparison to aquarium specific substrates) and it does not contain silicates. It is also much cleaner than play sand, so it will settle out much more quickly, and won't leave much floating in the water.