Hey there Asi! I got into hydroponics while still in college and I had the same problem, that everywhere I looked parts seemed to be so expensive. I knew this was a great idea and would work, I just didn't know how to get there.
Here's how I did it: I
I used plastic coffee containers and scissors to make little reservoirs.
Then you just need an aquarium pump to give oxygen to your roots so they don't drown.
I can send you a list of links to all of the materials I used for my build, I also wrote instructions, the end price was $154. It does not have all the automation components that these food computers do, but you can start to play with PH, nutrients, and other variables until you can fund other projects.
Here is a link to a video on the very basics of how I got started (the video channel on YouTube is very informative too).
I hope some of that helps!