If you are looking for a specific canopy I wouldn't do mailorder because you are allowing them to chose for you, for instance I got two diferent JM and their shapes are 180 degrees apart. One has a great canopy, the other is upright.

Here is a link that might be useful: Propagating Perennials

If you are talking about Autumn Moon and Aureum, both of them will eventually get much taller than 4-5 feet. If that is truly the height limit, you should be looking at dwarf varieties. Some nice dwarfs include Kamagata, Mikawa yatsubusa, Beni ubi gohan. There are many, many dwarf varieties. Kamagata has a lot of nice features -- leaf color, shape, hardiness, fall color.

The problem with many dwarf selections of J. maples is that they do not produce much of a canopy spread. While 'Mikawa Yatsubusa' is one of my favorite maples, it does not produce any significant branching structure and will never develop a real canopy. And it will take years to reach 4-5' :-) Ditto with cultivars like 'Shaina' or 'Pixie' (although growth rate may be faster).

But there are smaller growing forms that do develop a nice canopy spread - 'Kamagata' is one, although will remain quite short. You could also consider 'Katsura' or 'Ariadne'.

FWIW, although slow growing, Acer shirasawanum 'Aureum' will get to be a good sized tree in time - I've seen them 25' tall and equally as wide. 'Autumn Moon' will be similarly sized. See the photo in the attached link for a mature example.

Here is a link that might be useful:

Also, many of the dissectums could be kept within your height limit with lots of spread -- such as Filagree, Red Dragon, Red Filagree Lace, Ellen.