eric, the sandblasting sand was about $12.00 (US) for a 100 pound bag.
I don't know how much the live sand helps with the cycling? I used a 20 pound bag of it, along with a bottle of "Cycle" to help me cycle my tank. The reason is -- I completely re-did my tank by changing over to all new sand (dry sandblasting sand, about 80 pounds) and new dry, base "tufa" rock (about 30-40 pounds). I did not cycle my tank before putting my fish, along with a few mushrooms and zoas, snails and hermits in. I put it all in at once and did water changes every three days. I have no test kits, so took water samples to my lfs every 3-4 days for them to test for me. I fed lightly for the first couple of weeks. Everything did fine. I did not lose any fish, etc to the cycle.
I would NOT recommend doing it (cycling) this way (not much choice and was recommeded against doing it that way), but I only had 3 fairly small hardy fish that I have had for 3 years (one, a percula clown 6 or 7 years). So, in my opinion, it did help my tank with the cycling, but I have no proof other than that it was a fairly short/easy cycle. I never noticed any particular stress in the fish that I could tell. The ammonia and nitrites were there but did not ever get real high. It has been about 3 months or so since I have changed over. I'm going through all of the processes that new tanks go through right now (brown diatoms/and stringy brown looking algae on the rocks, also, I only use tap water, again not recommended), but the snails (need more) are really chawing (sp) down on that.
Just my experience. Again, I would NOT recommend cycling like that. I really had no choice except to take everything to the lfs which I did not want to do.
Good luck, Frank