Standard size for Cabbage Patch Kid clothing is 15-16 inches. Most doll outfits have the size located on the package.
Something like this..... Products like this do not hold their value. Ever since ebay came along the collectible value of items have severely gone down. You will not get more than 20 bucks for it.
I would say around $30.00. Most cabbage patch dolls have decreased in value. Here is a site that explains it. I can't say for sure which cabbage patch doll you have, but it doesn't sound like one of the really rare ones.