I'm sensing the core issue here is that you are afraid he is gay, and if you consistently guide him toward boy behaviors and encourage forming friendships with boys, that will keep him from being gay. I may be way off-base here, but I'm sensing that. Sometimes it's easier to talk about a concern if you shave it down to the bare nugget of it, rather than a concern about buying very expensive toys that are almost exclusively the property of the other gender.
Is that it?
An aside, there's a movement (among mothers, you will see) of turning American Girl dolls into boys. Because apparently there is a market for them, and boys want them. You might google it and see if your son is interested. Of special interest is the article in the New York Times:
I am sensing some toxic masculinity issues. Your son is not defined by the gender of the kids he plays with. Just remove all gender norms and expectations and let your son be who he is. I agree with your wife that your are in the wrong here.
I don't see why he cannot play with a doll, or only girls. He may find other boys to play with eventually- or not - it shouldn't matter either way, as long it all happens naturally. Giving boys what are traditionally considered "girls' toys" such as pink stuff, kitchen toys etc. is totally ok, and don;t we give girls cars, guns and what are traditionally considered "boys toys"? I think not labeling toys gender-wise may be the best course of action.
I am a woman and I played with pirate ships and castles. He is a child. Don't be a homophobe and don't be mean to your wife and son.