I don't spend any money on it. I've always joined late in the cycle and you can get an 'ok' team fairly quickly, I guess it comes down to how competitive you want to be. But if you are having to "save up a little bit of money each week" rather than just having loads of cash burning a hole in your pocket I would really steer clear of that as you will get buyers remorse, you'll get a short term hit from having a nice team but also feel ripped off by some inevitable bad pack luck, and then a couple of months down the line the cards you paid money for will become alsorans as more and more high rated cards get released.
With FIFA23 I actually joined via the mobile app early on and played for a couple of months before getting the game, just doing SBCs and a bit of minor trading, getting free packs, promo packs for 10 coins etc. Obviously without rewards you develop nowhere near the proper rate but it wasn't like I then got the game and was behind the curve for months, obviously I wasn't near the top echelons but equally it wasn't like every team was massively better. My team now I still don't have anyone rated over 93, but it's generally good enough, if I lose games it's based more on the skill of my opponent than what cards they have.
Don't be scared of joining late and using that as a reason to wait for FIFA24 (or equivalent), I joined FIFA22 when it went on gamepass in June and because of all the promotions you get high rated cards pretty quick. I ended up with a 198 rated team which was pretty good, only thing letting it down was I didn't do the 99 Dembele SBC so had 96 Torres at RW instead.
Remember that even if you find yourself outgunned you can use SBCs and offline objectives to unlock better cards and put you in a position to compete.
You'll always come up against the odd person with a ridiculous team of expensive cards which as mentioned above will be because they are either spending a lot, dedicating hours a day to trading or have been very lucky. No point trying to compete with that, it's like if someone on your street parks a 23 plate Lambo on their drive just accept it and move on, they've chosen to invest more than you whether that be money or time, or won the lottery, don't worry about trying to chase that dream.
That said I've got the bug now so probably the next release I'll just bite the bullet and pay the £60 or whatever is they are asking to play it from the start. I have a theory that a fun way to start off is focus on a strong silver team, because it's kind of self-perpetuating, if you do well in the Silver comps then you unlock special silver cards like flashbacks and stuff with ridiculous stats but "74" overall, so you can keep ahead of the competition. And then those special silver cards with artificially low ratings really help in the friendlies with caps on team rating because it keeps the average down.
Also don't forget EA aren't making FIFA24, so it's not really clear what the structure of their new game EA Sports FC will be, maybe it will be more weighted towards pay2win, maybe less, who knows.