I returned to sims 3, I don't think I can ever return to sims 4.

I agree with you. I love a lot of things in sims 4, but the way personality, or the lack of it, is handled somehow kills replayabillity. Like you said, sims act all the same.
About 3 price, go to instant gaming. I bought a few packs there. It's legit and you can put the codes in ea site and they're immediately available in origin. Packs are 3 to 7 euros. I bought 3 eps and payed something like 11 euros.