Here is one article that addresses a non-practitioner setting:
Sadoway DT; Loucraft JR; Johnston BA,  Maximizing influenza immunization in
Edmonton: a  collaborative model  Canadian Journal of Public Health, 1994
Jan-Feb, 85(1), p.47-50, 13 ref

Given the annual ads that I see for flu clinics at local Shoppers Drug Mart
and Walmart stores, I would think that there must be a favourable response
or they would not do it.  They contract nursing agencies to give the vaccine
on site.  Charges cover, at least in part, the cost of vaccine and the
nursing time.  My concern is that people who would be eligible for free
vaccine through their physician's office or health department end up paying
for this because of lack of knowledge re its availability elsewhere.
Joyce Fox