Plastic works fine.
My local shop sells one-liter, plastic bottles. These are dark plastic, which does not let in light. Probably not necessary, but that is what all they sell. These cost $2 each. Make sure to mark the caps so you don't put them on the wrong bottles. If you can find different color bottles and caps, it would help.
A graduated plastic beaker which holds one liter of liquid cost another $2. A good thermometer was $10. I would also recommend a funnel, which makes pouring chemicals from the beaker to the tanks and bottles (and vice versa) easier and less messy. I use a $1 egg timer, it has worked for years with no trouble.
My biggest expense was a used Jobo 2500 series tank with two 35mm film reels, which cost me $25. I got this tank because it can also be used for 4x5 film, with the appropriate reels. I like these tanks because they are larger, and the temperature of the chemicals is more stable. In smaller tanks, the chemicals cool down more quickly.
Developer was $3, fixer $8. So altogether, it was not a very big investment.
The actual process takes a little bit of practice, but is easier than making pancakes. If you are using 35mm film, you need to pop the end off the film canister, and remove the spool and film. I cut off the leader, then unwind the film from the spool (while rolling the film that comes off into a roll) until I get to the end, which is taped to the spool. I cut the film near the tape and toss away the spool. I do it this way because trying to slide the film into the film reel can be a little difficult if the spool is hanging or swinging around.
Now I have 4 Jobo tanks, and develop film in larger lots. I pour chemicals from one tank to the next as I work, and I find that I can get a lot of film done in a relatively small amount of time.
Rubber gloves are a must, in my case because the chemicals tend to draw all the oil out of my skin, causing the skin to dry and crack. I used to develop sheet film in trays, but this was very hard on my hands, which is the main reason I went with the Jobo tanks.
If you use D76 (my favorite) make extra sure that the powder is completely absorbed by the water, it helps if you are using a clear beaker, so you can see when it is fully mixed in.
A drying agent is necessary to prevent spots on your negatives, a couple drops of dish washing liquid will work in a pinch, but make sure not to get it bubbly, dried bubbles on your negatives is not good.
I hang the negatives from a laundry device used for drying socks, these cost a couple dollars here in Japan. I put clothes pins on the bottom of the hanging strips of film to keep them straight.
Once the film is completely dry, you may notice that it is not flat, but curved. I roll up the film, emulsion side out, and let it remain that way for a couple days. When I unroll it, it is completely flat.
If you use Rollei films, they remain flat. I love IR400 for infrared shooting, but also for normal black-and-white shooting, even though it is a little expensive.
Have fun, I like to watch Youtube fail videos as I am developing my film,
