Most VX Ace scripts are free for use now. Even some that were paid for use are now free. To know which ones are you have to find the CURRENT terms of use. For instance, CSCA was always paid for, now that he has a ******* account his scripts are free.
Yanfly is free, victor sant is free, other sites will have most scripts for free and only a few that are paid for such as Galv. Other sites are mostly paid for scripts with some for free, and they tell you right on the site, such as Dekita.
It's really up to you to do the ground work. Many scripts posted here in the forums that come from patch requests or new requests are usually free.
As you are new, it will take some time. I went through the process of trying to find all the scripts still available a year ago. Fortunately the wayback machine and github had some that were 'lost'. A search in my scripts folder for .rb and .txt shows that I have over 3000 scripts, but some of those are duplicates.