This can be a chicken and egg situation - to get a 504 or IEP it helps to have the initial eval, but those are indeed expensive.

With our son, we bit the bullet and paid $1500 out of pocket to get the eval, which lead to him being placed on an IEP. The school paid for about $7500 worth of additional testing and expert analysis after that.

I still would recommend a lawyer, but they cost as well.

However, without going through all of this effort, my 12yo with a super-high IQ would probably be suspended from school on multiple occasions. These kids really need help and the schools are legally obliged to provide it.