I have always purchased it from premium aquatics, not necessarily because it's cheaper but because it's the only place I found it.
I have a ton of flow in my 150 gallon, so I went with the reeflakes. They are a large grain size but it is still a nice sand. My 40 breeder is a sps tank, so it has a lot of flow to. I went with the miniflakes in it & it doesn't get blown around eighther. I like the look of a finer sand.
They sell a grain size inbetween the two, I believe it's called mesoflakes. I almost wish I went with that in my 150 & not the reeflakes. Don't get me wrong, I like the reeflakes a lot, I just prefer a finer sand.