You can make containers for growing vegetables from almost anything. Here is an example of a DIY Container:
How to Make a Cheap Tomato Garden Container from a Cardboard Box http://bit.ly/18mR618
For about $1.50 you can make a 1.5 cubic foot or 8 gallon tomato container box. Any cardboard box can be made into a vegetable planting container for under two bucks. If you use a box you have then you can do it for under one buck.
The video shows you how to make the container with a box, 2 trash bags and some basic hardware you can get in the electrical or plumbing isle of stores like Home Depot.
You can grow one large tomato in it. You could use it to grow two peppers. You could grow a cucumber in it. This is a great way to make inexpensive containers for your container vegetable garden. You don't want to get too much bigger then what I showed or the box will be hard to move around. You could get 2 seasons. Especially if you seal the PVC pieces with some silicon.
The video is from Gary Pilarchik's popular YouTube channel.
Please note: Most trash bags are not from food grade plastic and you should not store food in them. That does not mean you cannot grow vegetables in them. Most trash bags are made from plastic labeled as 1 or 2.