Ehh, maybe? Yakuza 0 is $12 right now and Kiwami 2 is currently $50 (going by USA prices). I swear Kiwami 2 has been on sale for MUCH cheaper than that in the past. On the other hand, it might not as readily go on sale because they might rather push people to this collection in the future. Also, if you don't keep Plus in the future, you'd still have Kiwami.
If I were you, I'd probably roll the dice and buy 0 for $12 right now (top 3 game of the generation for me) and play through that and Kiwami (play 0 first) and keep an eye on if Kiwami 2 ever goes on sale and jump on it. Also, many have said you can easily burn yourself out on Yakuza if you don't take a break in between games (more potential time for Kiwami 2 to go on sale). But on the other hand, $50 for the entire thing if you want it all now is outstanding as well. Either way you're doing well.
Awesome, thanks for the tip. Zero is real cheap in EU as well, but not on sale at the moment. I have both that and Kiwami 2 on alert on PSPrices, so hopefully they'll be on sale soon. And if Zero ain't on sale when I'm finished with my current game I'll go with your advice. :)