I want to get into the irl TCG but

I don't know what your experience is with the game, but if you have friends who play, ask if you can borrow their decks and try playing with them to get a feel for playing in paper. It is a little different to using TCG Live. There is no client to track the game and enforce the rules for you.

Don't buy booster boxes to try to build a deck haphazardly. Look at competitive decklist and work towards buying the cards to build one.

Usually the top deck(s) will be expensive to put together, but there are often lower tier budget or rogue decks that you can pur together and still potentially win tournaments, provided you are good enough and the meta accommodates it.

The plain, common versions of cards play just the same as the shiny ones. If you want to play cheaply, don't waste money on bling.

And since Pokémon's main format is a rotating one, don't buy a deck with lots of cards close to rotation. See if you can find one where the majority of the cards (especially the main play makers) are fairly new or at least have another rotation in them.

And lastly, don't be afraid to trade or sell your cards if the deck loses meta relevance or rotates out. Trade out months in advance of rotation if you can. Otherwise you will lose that capital you need to build your next deck.

Those would be my tips for anyone looking to play a card game in paper, particularly if it is a rotating format.

My point was "buy the cheapest version". Usually that is the most common version, but it is worth noting that it is not universally true.