As mentioned earlier, the proper tool for the job is called a screw-cap culture tube. I know that it's just a minor difference in terminology; however, it pays to know the proper terminology when ordering from a supply house. If one asks for vials when placing an order, one will receive vials. Most vials are made from soda lime glass and come with paper or foam liners. Neither of these liners is a good investment, and soda lime glass is not designed to withstand multiple trips through an autoclave.
As mentioned earlier in this thread, a screw-cap culture tube looks like a test tube with a screw-on cap (i.e., culture tubes have round bottoms). If at all possible, one wants to purchase reusable screw-cap culture tubes with reusable phenolic caps and rubber liners. Polypropylene caps will work, but they are considered to be single-use caps. The reason why culture tubes that ship with polypropylene caps are cheap is because they are designed to be thrown away after a single use.
20mm x 125mm Screw-Cap Culture Tubes
The culture tubes shown above look similar, but the one of the left is a Corning 9825-20 20mm x 125mm reusable culture tube with a reusable phenolic cap. The culture tube on the right is a disposable culture tube with a polypropylene cap.
Culture Tube Caps (exterior surface)
The cap on the left in the photo shown above is phenolic. Notice how it is less shiny than the polypropylene cap on the right. That's because the material from which phenolic caps are made is combination of cellulose fiber and phenolic resin. It is a thermoset material that does not melt.
Culture Tube Caps (interior surface)
The phenolic cap on the left in the photo shown above is much thicker than the polypropylene cap on the right. Phenolic caps do not flex.
There is a cost difference between reusable culture tubes and disposable culture tubes. Quality reusable culture tubes usually cost between $2.00 and $2.50 each in quantity. Culture tubes that costs less than $2.00 each are usually made to be thrown away after a single use. My preferred culture tubes are Corning (Pyrex) 9825 and Kimble-Chase (Kimax) 45066. Corning 9826 culture tubes are also very nice, but there is no need to pay extra for a PTFE surfaced liner. One can often find good deals on NOS and used culture tubes on eBay. However, I would refrain from purchasing NOS or used culture tubes that do not come with caps. It's difficult to find reusable caps in less than quantity 192. One needs to remember that the keyword here is "reusable," as there are disposable phenolic caps.
Answering Peter78's question, yes, the investment is worth it if one looks at yeast management as a sub-hobby within the brewing hobby. I have brewed with cultured yeast since my fourth batch of beer. My first home lab easily paid for itself. The key to building a self-supporting home laboratory is to purchase wisely and only purchase what one is going to use. It is easy to get carried away with labware; therefore, I recommend starting small and adding additional labware as needed. The minimum setup that one needs to culture yeast is a pressure cooker that is capable of at least 13 psi (15 psi shortens the amount of time that media must be pressure cooked), twenty culture tubes, a nichrome loop, and an alcohol lamp (a.k.a. a spirit lamp). A large-capacity pressure canner is nice to have, but a 6-quart pressure cooker will handle most culturing media needs. In fact, I have been using the same 6-quart stainless steel pressure cooker for over twenty years. While I currently use 100ml Corning media bottles for canning 40ml absolutely sterile starters (used when propagating yeast from slant), I used 4oz baby food jars for years (use jars that contained fruit or vegetables). The lids on baby food jars will reseal after autoclaving. However, they are only good for a couple of passes through a pressure cooker. The glue residue that is left on a baby food jar after delabeling can be removed with "Goo Gone" or mineral spirits.
I recommend using pre-poured disposable plates until one becomes comfortable with making sterile media. Making plates correctly is considered to be an advanced skill. Contrary to what one will see on YouTube, properly made plates are never placed in an autoclave, as autoclaving plates results in too much condensation forming on the inside of the lids. Glass plates are usually made by dry sterilizing the petri dishes in the oven, autoclaving the media in a separate container, and pouring the plates hot after the media has cooled to between 120F/49C and 140F/60C. Another thing to consider is that quality 100mm borosilicate plates such as Corning 3160-100s cost around $7.00 each plus shipping. Plates are only used when adding new cultures to one's bank (as I mentioned earlier in this thread, one should plate for "singles" before adding a culture to one's bank to ensure purity); therefore, glass plates are a luxury.
If anyone is wondering why he/she should learn how to plate and slant, here's a photo of a new culture that I am adding to my bank:
The culture on the plate shown above is Scottish and Newcastle's Tyneside culture. Each of the well-isolated round colonies is composed entirely of the offspring of a single yeast cell. Single-cell isolation is how we purify a culture.
Learning how to plate and slant yeast means that one is freed from the selection constraints imposed by the major yeast suppliers. The culture shown above is not available from Wyeast or White Labs. None of the cultures in my bank are directly available from Wyeast or White Labs because they are either brewery cultures or cultures that I acquired from culture collections.
Here's my current collection: