I have a stirplate, flasks in 2L, 1L and 500mL sizes and reckon I could make do with just the two smaller flasks and a whole bunch of PET containers like those shown below.
My procedure is as follows - once I've got a small amount of yeast to get a starter going (whether from a slant filled with wort or a bit from a previous saved yeast or smack pack) I put it into ~500mL of wort on my stirplate and let it stir away for about twelve hours or so.
I then pour the first lot of starter into 1L versions of the PET bottles shown in link below and set aside. I then prepare another 500mL or wort by boiling (have been using old kit concentrate recently) and pouring into the water and sanitiser rinsed ehrlenm. flask for a bit more boiling, cover with foil and allow to cool down in a cold water bath.
When it's cool enough, the first lot of starter should have mostly settled so I pour most of the beer into a glass for a taste test and assuming it tasted ok, I shake up the remaining settled yeast - pour most of it into 250mL bottles like those shown below and the remainder into the flask for the next batch of starter.
I basically repeat the above cycle several times - combining batches of yeast (checking with taste tests of the beer or added boiled/cooled water, of course) until I've got enough yeast. I can grow about 120mLs of settled yeast after about 5 or 6 cycles over several days, which is like about 2-3 vials of Whitelabs yeast.
With rinsed yeast slurry from previous brews, I can just go right into the last stage to refresh the yeast.
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These bottles are great but haven't seen them around for a long time - there are drink bottles like these that could be used, sanitation is key (including pulling out the cap liners when cleaning).
