I have to agree. A bunny litter can be more than 6 bunnies at a time… if your cousin wants a pet bunny I would just say get the one and not 6 right off the bet… 1 bunny alone is a huge responsibility let alone 6 plus mom and dad.
My Rookie did the honking, circling, and actually spraying pee mid binky before he was neutered. The vet said if the behaviour of spraying and biting is let to be going on for an extended period of time then yes a neuter may not help as the bunny will consider the behaviour every day and allowed. But fi the neuter is done within a good time frame of the developing negative behaviours then it can be resolved with it. My Rookie never sprayed pee again and unfortunately did also stop his honking and circling as well which I did actually miss after.
neutering and spaying does help with these behaviors. The costs depends on where you are…but spending on treatment for a bunny that is fighting cancer is a lot more in the long run. I think for Rookie it was about $300 give or take a few $10’s to be neutered in Toronto, Ontario, Canada