I wouldn't buy Japanese maples at ebay. True cultivars are grafted and it's best to buy these plants from a reputable source.
Ebay can be a good source for inexpensive maples, just because they are on ebay doesnt mean they are not grafted. The trees are smaller and take some care for a year or two, but for the price a good way to get some that you cannot find locally. If you are going to put them out into a tough enviroment, you might want to try something more mature and possibly local. Yes some on ebay are not as good as others, but that is just a fact of life with any type of vendors. Mike
They are smaller and depending on the source they can be pretty good! I bought this oridono nishiki from the same seller that i got my shin deshojo from and he uses good soil mix and arrive healthy! I did buy a katsura from a diff seller and the soil sucked it was compact and retained water which fugged up the roots they looked like worms the roots! and took a year to recover but now it's doing great!