Yes, I started my first tank without LR and just bought a bunch of Lace Rock..I do not recommend lace rock though...I agree with maiceman in that you can use just the Southdown if it is available and then just add a cup or two of sand from a friend or your LFS if they do that..I have a LFS that sells LS at $2 per pound...It actually is in a tank and has critters in it...The stuff in the commercial bags is a bunch of hype. Don't waist your money. After a few months, you rregular sand will start to be live anyway...adding the LS will help speed up the process.
You may want to also buy a few pounds of LR so just as was mentioned, the critters will migrate into the sand from there.... I made my LFS dig the rock from the bottom of the pile next to the sand so that I could get some of the critters that were growing on or in the sand around it....He he...
I also bought a little LR at a time. however, it is much more expensive in the long run...hind sight being 20/20, I wish I would have bought it all at one time..much cheaper that way.. Most LFS's charge in upwards of $10 per lb for LR. 80lbs is $800 that way... not economical that way IMO. but, like I said, Hind sight is 20/20.
If you can't find Southdown or Yardright sand, you may want try
Pure Aragonite for sand. a little more expensive, but good stuff.