Brand new player little to 0 knowledge.

My buddy at work plays and has a bunch of decks. I have been playing/learning the past week. We have played probably 6 games so far. I’ve been using random decks he has but would like to have my own to play so I can really learn it. He has $100-$1200 decks. Is there something budget that I can get to compete? I also have no idea how to actually “build” the deck. I also like the collaboration decks like Lord of the Rings and things like that. Any and all help would be super helpful! I don’t need a another hobby but here we are lol 😅