I found a seller at Amazon, and I was wondering if anyone has had personal experience with them? They sell a lot of 2-year grafts of rare cultivars of J.maples, and pines. They seem legit, and the reviews sound good.
Use Diana from www.topiary-gardens.com
Huge trees. Cheap. I have over 50 trees from her. Tell her John Caro told you about her.
Keep in mind that having a grafted trunk on a bonsai is very undesirable. It usually just looks bad, and the rootstock portion of the trunk will swell larger then the rest of the trunk and it will only get worse over time. I made the same mistake when I first was looking for japanese maples. Most japanese maple cultivars are grown as grafts, so be careful what you buy.