Halka has large trees, but you may need to go through a landscaper.

Condurso in Montville and Richfield Farm in Clifton could be worth a call. Also Orange Garden Supply in Orange. Even Center Ridge in Nutley, which is smaller in general, had some gorgeous big trees in the spring; probably not so many now.

There is a place on 202 in Oakland that sells large trees - real speciman stuff. Can't remember the name but it is close to the memorial near Terhune Avenue. They aren't cheap though.

Thanks Loretta

Is it Riverside your thinking of?

Probably. It looks that way on the map. You have to drive down hill a little. Did you try there already? They had the most impressive collection of trees that I've visited around here.
You know places like these will order the trees for you though they probably are not digging until the fall now.
Condurso's was mentioned...not sure I saw the 12-15' range here but I don't walk out the back area usually. Usually I see the JP under the shaded area and they have been smaller than 12-15'.
There is also Eiseles Nursery & Garden Center on 232 Oradell Ave in Paramus, NJ 07652.
Fairfield Gardens in Fairfield (on sale now) is worth a check. They always have trees in the back and might be more reasonable too.
Then there is Max is Back in Butler on Route 23. They have a limited number of larger plants. You might call first. Same with Birch Hill Farms on Newark Pompton Turnpike in Wayne, not far from where Packanack Lake road starts. I think they are the most expensive of the group but nice plants. Again, call first.
There is one more small place on Wyckoff Avenue, starts with an H...

Not in your location and you would have to have the means to transport but Ambleside Nursery in Hillsborough had a nice variety of some beautiful JM when I went yesterday.