You can't get 4s kabuto this week. 100 frags of minato cost 22k in summer memories shop. By spending 30k in great tree, you can get 100 frags of edo madara. With some luck, you will have coins left over to 4s your kisame as well. 80 more madara frags from fuku pack, but don't open it just yet (theres a 0.000001% chance he is a 3s break) in that case kakuzu is a good ninja. Or you could start collecting frags of naruto or kabuto. In my opinion, 30k into tree is the best choice and naruto/madara/kisame are all good ninjas to get.

I see, I don't remember how many coins I got when I did the tree.

Its better to recruit them, it gives a small amount of power.