I looked at the Mr Maple website. I would expect 100% of their Japanese maple trees to be grafted. With maples, the smooth bark of the trunk is an important feature. It is very rare that with a grafted maple the graft union heals smooth enough to make a exhibition quality bonsai. You can have a pleasant tree for your back yard, but as bonsai the graft union will likely be a serious flaw. The Mr Maple ginkgos are also grafted trees, and the same warning applies for grafted ginkgos. Any tree purchased from Mr Maple would be excellent as a landscape tree but likely unacceptable as bonsai. Sorry.
I suggest you only buy cutting grown japanese maples, and currently Evergreen Gardenworks is the only nursery I know that sells cutting grown Japanese maples. They have more than 12 different cultivars available as cutting grown stock.
https://www.evergreengardenworks.com/