In LA at least, this is common among high end restaurants. Certain chefs have relationships with specific farmers, or they have food buyers select the best produce at the Santa Monica Farmers Market. I suspect most restaurants just buy from normal distributors because it's cheaper though.
I've also noticed this with better restaurants. I think specialist buyers and distributors will continue to serve a role; and so will farmers' markets. But my thought is it's better when shareholders buy-in for a season. The farmer gets more operating capital up-front and spends less time on sales during the harvest, because distributions can be figured out ahead of time.
