Much higher costs far exceed the advantage you gain from transportation. If you manage well you will have higher yields but not enough to overcome the hole you're in.

You will be able to charge higher prices but outside of a couple of cities the market is too shallow consisting of basically very high end restaurants. You're saving the chef having to go to the farmers market and having lettuce that is say twelve hours fresher.

Don't underestimate a savvy farmer from making deliveries and undercutting your advantage because in some cities it's already happened. Or a Detroit startup I know that is picking up from the farmer and making deliveries, chefs can order from their cell phone.