$12 will grow about a hundred gallons of the stuff I would guess!
Wilkersons clownfish book has some good info. but web resources are:
Frank Marini's articles
Rob Toonen's article- well referenced and detailed
There was another article on reefkeeping magazine but it doesn't come up on google. It had a compact station with lights in the middle and bottles on both sides. I used to have something like it....
I culture at 1.020, room temperature, with a 24x7 photo period with 2 24" NO plant bulbs. I usually only have 2 bottles going at a time. I find doing more than that too much work and I've not had problems with cultures crashing out. I usually use algae disks to start the cultures, or some fresh stuff that you can find on e-bay pretty cheap. The last batch I just used a capful of fresh DT's. One of the strains obviously outcompeted the others by this time. I use either used juice bottles or 2 L soda bottles (clear) when they get gunky, I just throw them out (after taking some of the culture to start a new bottle). I feed half a bottle of dense culture between all the tanks every other day roughly. Was a bit less in the winter as the colder temp had the cultures growing slower.
A fun page for phyto:
All about phyto from wikipedia
Another store with a bunch of live goodies
the other 2 main ones are floridaquafarms.com and aquaticecosystems.com
The bible of plankton culturing if you really want to get serious (no I don't own a copy)