What is a cheap & good kind of Sand for goldfish & plants?

1) playground sand – may cause cancer

2) all purpose sand – may cause cancer
may contain silicates & harmful dust

3) patio sand fine

4) patio sand coarse – may cause cancer

Most plants don't even like sand. Its mostly used as accents in tanks. Goldfish also don't do so well with sand. I would recommend gravel or those tiny pebbles.

ADA sand is a little pricey but its the best. Besides that I've heard a popular choice is playground sand. Make sure it has no chemicals added and that it isn't calcium carbonate.

Most often substrates such as Flourite are used in planted tanks

yeah, I want some inexpensive sand on top
and I think there are more choices for the richer bottom layer

I wouldn't recommend using sand for goldfish. Keep in mind that if you use sand as a top layer and something gravel-like as a bottom layer, the larger particles will eventually work their way up and end up on top.

I think lots of people use sand with GF successfully

I don't know about the plants, but I hear very coarse sand is fine in goldfish setups. However, I'm not very familiar with the sand you've listed, so I don't know which is best.