Many people have these questions when it comes to buying property here, and, in your case, as a young family, some other factors you might also want to consider wrt choosing a home with Mello vs.no Mello, involve your choice of school districts, as well as how much time you want to spend commuting.
We have some rentals in Carmel Valley that have low or no Mello, so they do exist there, as well as in some other extremely desirable locations of the county, and any realtor should be able to provide you with that information.
Right now, it’s a huge challenge to find a home in the most desirable areas of the county, but, believe me, it’s worth the effort trying to find the home and location you really want–vs. settling for less–especially if you’re here for the long haul.