Bit of an investment up front (Just did a quick check on Amazon... 31 bucks for the 2 vials, agar agar bar and a beaker set) but once u do, I don't see why u couldn't just rehydrate and entire dry pack, then slant it. U'd be reusing everything except the agar agar and DME. The OP says some of the slants can last up to a year and a half. He makes 25 at a pop and will use 5-6 slants per strain. Ideally u could do that and end up saving the money at the end of the year.
One does not need a beaker to make slants. I maintained a yeast bank for a decade before taking over a decade long hiatus from brewing (I am currently rebuilding my brewhouse and home-based lab). The only thing that one needs to purchase in order to be able to slant yeast is a pressure cooker with which to autoclave (pressure cook) one's slants. I used 4oz baby food jars that contained a fluid ounce of 1.030 wort solidified with agar when I first started to slant yeast over two decades ago. My first loop was a paper clip.
With that said, three really nice to have pieces of lab equipment are an alcohol lamp (burns denatured, grain, or 90% isopropyl alcohol and is much safer than a Bunsen burner in a home-based lab environment), a reusable nichrome loop, and 20+ screw-cap culture tubes (one can use a turkey baster to fill the screw-cap culture tubes with media). The culture tube sizes that work best in a home-based bank are 16x100mm, 25x100mm, 16x125mm, and 20x125mm. I just picked up a set of twenty autoclavable 20x125mm screw-cap culture tubes on eBay for $29.00 shipped (
http://www.ebay.com/itm/20-Glass-Cu...121?pt=LH_DefaultDomain_0&hash=item19cdefb8e9). Better deals can be had if one is patient, but one needs to ensure that the caps are autoclavable (i.e., can handle 250F @ 15psi). I just purchased a loop and an alcohol loop from Home Science Tools (
www.homesciencetools.com) for $17.80 shipped. I like the loop shown below because the tip comes off.
Loop
http://www.hometrainingtools.com/inoculating-needle-looped-end/p/BE-INOCUL/
Alcohol lamp
http://www.hometrainingtools.com/alcohol-lamp-glass/p/CE-LAMP2/
In order to start yeast from a slant, one must prepare autoclaved 30ml 1.030 wort sterile starters (like ones slants, 30ml sterile starters need to be pressure cooked for 15 minutes after the pressure cooker starts to make noise). One can use expensive lab glassware for one's sterile starters, but 4oz baby food jars are a perfect and cheap fit for the job, especially considering that they are usually one man's/woman's trash. One has to remove the labels and glue from the jars, but a little soaking will loosen the label and "Goo Gone" will remove the glue residue. The neat thing about baby food jars is that they will vacuum seal if one tightens the lids down after removing them from the pressure cooker. Their lids will make a loud pop. An autoclaved, vacuum-sealed 30ml sterile starter will remain sterile for years if kept in a zip lock bag in one's refrigerator (the zip lock bag just keeps the nasties off of the outside of the jar). Baby food jars can usually be autoclaved several times before the seals on the lids give out.
The basic procedure for starting a from a slant is to transfer a loopful or two of yeast from a slant to a 30ml sterile starter using sterile technique (a.k.a. aseptic technique). One only needs to crack the lid on the baby food jar enough to be able clear the jar's lip and lid with the loop. After the sterile starter has been inoculated with yeast from the slant, the lid is tightened and the jar is shaken to oxygenate the wort and disperse the culture.
One should be able to hear the hiss of gas escaping when the cap is loosened after 24 hours (some cultures can take up to three days). The 30ml sterile starter should be propagated to a 250ml boiled 1.030 starter on day two if gas was present when the cap was loosened (sometimes one will have to wait several days to perform this step). A 1000ml Erlenmeyer flask with drilled and non-drilled #8 stoppers makes this step easy, as the starter wort can be boiled and cooled in the flask by loosely covering the flask mouth with a piece of sanitized aluminum foil while it is cooling (I spray the foil with alcohol and allow it to flash off before cover the mouth of the flask). The stoppers need to be boiled in water for 15 minutes.
After the starter wort has cooled, the 30ml starter is transferred to the 250ml starter by swirling the yeast into suspension, wiping the mouth of the 30ml jar with a cotton swab that has been soaked in grain or 90% isopropyl alcohol, burning off the alcohol using a butane lighter or an alcohol lamp, and pouring the contents of the 30ml jar into the flask. The solid rubber stopper is then pressed into the mouth of the flask, and the flask is well shaken before replacing the solid stopper with a drilled stopper and an airlock filled with grain alcohol.
The 250ml starter should be stepped to a two-liter starter on the following day. The two-liter starter is pitchable. The mouth of the two-liter starter should also be swabbed with alcohol and flamed before pitching into a batch of wort.
If this procedure is followed religiously, one can repitch the yeast without worry, as long as one swabs the lip of one's carboy with alcohol before taking a crop. Most infections are the result of improper starter handling. If one follows my procedure, one's yeast culture will be cleaner than anything one can purchase in the homebrew trade, including anything from Wyeast or White Labs.
Please note that everything that one uses for culturing has to be dedicated to culturing. For example, one should not use the household turkey baster to fill the culture tubes with gelatinized wort. One should also purchase a dedicated box of cotton for transferring cultures. Yeast is the single most important ingredient in beer. How it is handled makes the difference between an okay beer and a great beer.
