If you take sand off the beach, just boil the crap out of it several times and it should be alright. You can also go to the store and get a large bag of regular playsand. It's not as pretty but it is still alright, the only downside is you will see a large diatom bloom initially on it.
, save for a bit and get the aragonite. A couple weeks/months/years down the road, you'll wish you did and its a pain to swap out. I wouldn't buy live sand, chances are by the time you get it, most of the stuff will be dead in there anyway, and its a big bag of nitrates.