You can use play sand in a pinch. However, grit is very inexpensive but they quickly outgrow the 3 sizes for chickens.
If I just had a few chicks and wasn't going to get more any time soon, I'd stick with the sand till about 3 weeks if large fowl, 5 weeks if bantams.
Chick grit is useless for older birds.
If they only have chick starter they don't absolutely need grit but it does help develop the gizzard.
I would just sprinkle some of the smallest particles of sand on top of the feed once or twice the first week. After that put a little in a separate container.
If you feed things other than starter, (which I don't recommend) they must have appropriately sized grit.
In the following link there is a list of grit sizes and the ages they are for.