If you don't have\can not get the multisite option (which I recommend you do if you have 10 sites)
You can actually have all the sites use one database by creating different user accounts and not associating them with the same schema (ie not dbo)
What happens is that each user account ends up creating all the tables for Sitefinity prefixed with the user as the schema
Down side is that you will have 10x the number of tables.
I have never actually tried it. I usually end up fixing it when people have run into the issue. I haven't actually tried\implemented it but I think I will give it a go when I have some time. It will be interesting to see the result.