Are these hard to come by with good grades and good ACT scores? I know many kids here are top notch;
The Univ of Notre Dame has virtually NO merit scholarships.
So, yes, they’re hard to come by since they really don’t exist.
The regional alumni clubs may offer some small one-time awards.
I think there’s something called the Hesburgh -Yusko scholarships given out by the school that are merit based. I’m not certain but I think it’s for 100K over 4 years. I recall some threads about them from other posters on this forum in the past.
Notre Dame actually has several merit scholarship programs. There’s the 1) Stamps scholarship which is full tuition that they give to 5 students, and then they have the 2) Hesburgh - Yusko scholarship which is more service based, that they give to 25 students, worth at $25,000 a year, 3) Trustey scholarship which is also $25,000 a year given to 4 or 5 students that is mostly based on academic merit for kids who show strong interest in science or engineering (strong science extracurriculars are also necessary here) 4)Notre Dame scholar award which is also $25,000 which i think they give to either 10 or 25 kids, not sure whats the criteria for this one, probably overall very very strong academic and extracurricular applications 5) Penelope and Walter Scott scholarship which is for 5 kids at $25,000 a year which is again for i think just overall very strong applicants.
So basically, there are definitely a few options in merit scholarships. I know that besides these “named” scholarships they also give merit scholarships ranging from $10,000 to $25,000 to a few other students. That being said, remember that there are almost 20,000 applicants to Notre Dame per year, many of them being merit scholarship worthy so the chances of standing out enough to actually receive merit aid is very difficult, no matter how strong your application is.
But not impossible 
GOOD LUCK!
btw, the only scholarship that you have to apply for on your own is the Hesburgh Yusko one, the rest they will contact you if you are being considered for it! For most of their scholarships, they’ll tell you if you got it early April, so you’ll have to be patient!
There are, of course, also athletic scholarships offered by Notre Dame. But by and large, the bulk of aid offered by ND is need-based. And remember, THEY get to define “need”, not you.