97x150 pixels. Generally if you want to make a journal doll or a page doll, you're going to want to keep the dimensions 150x150 pixels or smaller so that you can use the thumbnail code without a preview image.
You have to remember, (I'm not saying the artist is like this) some of the people here...don't have anything except for art, and maybe education. They might not have jobs because time might not allow, so...
$10.00 would be underselling myself quite a bit, since these take 3 hours on average to make. $10.00 would mean I make about $3 an hour, and quite frankly it would be difficult to buy lunch on those wages.
There's a difference between buying a video game and buying a commission. When you purchase a video game, you're purchasing one of thousands of copies of a thing that already exists. When you commission an artist, you're asking them to create something specifically for you, but that artist can really only sell their commissions one time each.