How can I grow lots of shrooms, fast?

The fastest way to get lots of mushrooms (of any kind) is to use grain spawn with bulk substrates, inoculated with a select strain from a clone which has evinced quick colonization as well as quick fruiting capabilities, and of course huge returns. You would want to start with a 21 quart presto @ $80-90 or optimally a AA941 @ $400. Jars are good but grow bags fill your pressure cooker more effectively and will give you more spawn per PC cycle. Grow bags typically require a flow hood due to their size, while they can still be done in a glovebox/SAB. The cheapest and easiest way to build a fruiting chamber would be a simple monotub(s) in a room with some basic fluorescent lighting and light air circulation ie ceiling fan on low. 

To be honest, there is no quick and dirty way to start producing massive flushes from the start.  A multispore (MS) inoculation (say a spore syringe inoculation) can give very varying yields.
Most experienced cultivators select and isolate their strains based on big fruits or vigor of growth on agar plates.  If agar work isn't an option you can always go with your best growing MS jar and GTG that out to more jars. Another key point is understanding what the pinning triggers are, how they work and when to start fruiting conditions.

If you are new to growing mushrooms and are here with the intent on making a fast dollar you will come out very disappointed. You will probably fail at the first bulk grow. Do not start running if you never learned to walk.

PS This website does NOT condone the sale of mushrooms - so asking questions how to become a cash cropper will, at best, get ignored (and at worst, get you flamed an banned).
Save yourself the trouble :)

~virus1824