there lies the fun of the game but not that i know any better but i'd guess maybe just the food one if you're worried more about them striving (i'm guessing that in food development it's more related to their health than advertising development?) and then leave the rest of the money for buying semi rare eggs (it all depends how much money you got anyway)

edit : also, do you have a lot of the items in the second row, like the starfish and some of those plants? I think those are probably also essential for the rarest species even with research? (just a guess)