CYN-
If you are a LFS and you have the option of selling a 50# bag of SD sand for $3.49 or a 30# bag of Caribsea sand for $35.00....which would you choose to sell. It all comes down to the dollar.
However, this philosophy really does not make sense if you think about it. If you are starting up a reef tank and spend $235 on 200 pounds of Caribsea, that is going to be a one time big purchase that is going to put a small strain on the wallet. But at that point you have spent 235 bucks on something that requires nothing to maintain. Instead Say you bought 200 pounds of southdown sand for $14.00 at the LFS. And then in three weeks the sold you fish, corals, lights, etc to make up the other $221 from not selling you the caribsea. Well now you need buy additives, buffers, etc.
Basically what i am saying is it make more sense as a businessman to have a customer spend money on a product that will always require maintanence (fish, corals, etc) as opposed to something that won't(sand)
Amen....my preaching is done..i am steppin off the soap box!