Hippie...seems like your sandbags are a good inexpensive way to go especially since they are on sale now. And also compared to some other very expensive kits that are out there. Especially with the expected results.
:eusa_clap :eusa_clap :eusa_clap
(So I just add spawn and that's it?)
Spawn, place on top of black plastic sheeting, keep dark to colonize if you can, give light in about 6-8 days, place a fan (oscillating works best for multiple bags) blowing on the outside of the bags and wait for harvest.
The most trouble you will have is harvesting. You need to make sure you pull all aborts and peices of fruit out that you possibly can. It can be tedious and take alot of time, but if you fail to remove everything you will have a mess of bacteria infected rotting nastiness. Sandy Tip: Wear latex gloves and wash your arms before you go sticking them in there to harvest.