If a school my DS wants to transfer to is transfer need-aware, will he have a hard time getting in if he is applying for aid? Is it worth it to even apply? I’ve heard that for transfer students applicants are looked at last if they are applying for financial aid.
Each place sets its own policy about this, so ask them individually.
The important thing to remember about “need-aware” is that the aid will be found for students they want. Students who are borderline, or equivalent to others who need less aid, are the ones who are rejected or gapped.
@happymomof1 is right in that you should contact the school of choice, they’re usually very open to giving that information, which is commonly found on their sites too. I can see where the confusion would come in though as some schools are need-blind for freshmen instead of all applicants(e.g. Bowdoin, Brown). Google search “Need Blind Admissions” and go to the first Wikipedia article, last time I checked it was pretty accurate (and states when a school is need aware for transfers)
I feel bad to say it, but yes, he will have an extremely hard time getting into a need-aware school, directly proportional to the amount of need he has. I was in the same spot last year and that was by far the biggest anchor in my application, money. The universal problem, but at the same time the solution.
We don’t have enough information to make recommendations of schools, but good luck to him! Get researchin’ 
https://www.edvisors.com/plan-for-college/college-admissions/need-blind-admissions/
A great resource. I’d double-check by contacting the school though. Best of luck!
In the absence of specific information about the school, there’s no way to know if it’s worth it to apply; if the transfer financial aid budget has not yet been depleted and the school wants him, he may well be admitted. The school’s Common Data Set section D2 gives transfer applied/admitted/enrolled data, but nothing about financial aid.