It came in a 4x4x10 in. pot
I'm a little unsure about the dimensions of the pot. Are you saying that it is 4x4 in area and 10 inches tall? If so that would be a cascade pot, for a tree that hangs over the rim of the pot. If your tree is 10 inches tall it does not sound like a cascade. Depending upon your plans for this tree I would consider a wider and shallower pot to allow the roots some room to grow. If you are satisfied with the current image it presents you could keep the new pot a little on the smaller side. If you wish to encourage growth , a little on the larger side.
Don't feel that it is necessary to purchase a ceramic pot either. I know everyone wants to have a finished bonsai in a nice pot but sometimes that can be counterproductive. Again, this is dependent upon your goal for this tree, but bonsai are usually grown out in common nursery containers that have been cut down or other containers known variously are growing boxes or training boxes. Only when they approach completion are the placed in proper bonsai pots.
There are also plastic containers that are inexpensive but look like unglazed terracotta. These come in various sizes and can serve you well in the early years of bonsai development.