John,
The forum has strict rules against discussing illegal activities, and since net fishing can be illegal, it would be well for you to get to grips with the legal aspects so that you understand what can be discussed and what cannot. This will also allow you to steer the discussion in a direction that is useful to you.
While questions about what fishing gear to buy to get started are pretty common...starting in talking about cast nets is not common.
Help us out, back up a little and tell a bit more about what kind of fishing are you getting into? I know something about fresh water fishing but much less about sea fishing. What is it that you are embarking on, how have you got interested in it? While I have seen cast nets used for catching bait in various YouTube videos from the US and other places, I have not heard of their use in the UK (where they would only be legal in some areas of the sea). Normally when people talk about the hobby of fishing, they talk about rod and line, which is less efficient and catching and killing fish than nets (or traps, or dynamite) but is more fun.
I am sure you are as able to use Google as anyone, and that would be a good start.
Not sure if this belongs here or in "Fair Game" - mods, feel free to move it. ;) Anybody know much about castnet fishing? Is it legal in the UK, and if so, is it worthwhile? What species would you be likely to catch?
bushcraftuk.com
The Environment Agency is warning anglers that fishing with an illegal cast net could result in a hefty fine or even custodial sentence.
www.gov.uk
The other aspect of your question has fundamental implications for all equipment purchases. The usual advice is to buy the best you can afford at the outset, that way you only cry once. Certainly this applies to tools where poor quality tools wear out more quickly, or are more difficult to use. Lots of people have found they wind up spending more in total by buying cheap, then a little better, then a bit better still before eventually buying the one they should have bought to begin with. Of course, no one tells one how to judge affordability! There is good inexpensive gear, and there is cheap junk, but without specific examples its hard to get specific advice.
Buying with the expectation of cheap gear being disposable is something else, something that I do not think should be encouraged. Think on this. Nets are invariably made of man-made fibre. How is buying cheap kit that you plan to throw away, and in doing so create more plastic rubbish, in keeping with any kind of environmental responsibility?
Looking forward to hearing from you, as I say, you have asked a pretty unique question!
ATB
Chris