I will say the only thing I 100% do not want is a game where I have to buy 'decks' beyond the main game - I hate that.
Nope. No purchasing anything beyond the initial cash. I mean, there are further characters you can get for both games but it's something you can wade into and then run away from in an economically painless way if you find it's just not for you.
Rodney's "Watch It Played" vid may help you out.