In New Zealand, we have Music Centres, either unincorporated societies, or incorporated societies, attached to Intermediate Schools. The Centres cater for children usually between 7 and 12 years of age. Although using group teaching, classes are kept small, trying to cater for students at a similar level. Class sizes are usually capped to ensure the principle of small groups,allowing some personal tuition, can be met.
The Centres employ professional teachers, and usually a part-time administrator. A range of instruments is covered, including guitar. Teaching is usually done Saturday mornings. Otherwise, the Centres are led by a committee of elected parent volunteers who also assist with desk duties, etc. when the Centre is open. I was a Treasurer and then Chairman of such a Centre for many years, with maybe 20 tutors and some 300 students.
I think the system works well. The Centres fit between what Primary and Intermediate schools can offer, and private tuition. After 13 years of age, children move onto High School where they can get more dedicated teaching, or private tuition if they show real promise. Children get an opportunity to experience music and decide later if they want to go deeper with private tuition (if their parents can afford it). It gives better access to good music education to lower socio-economic children, some of who are very talented, who would otherwise miss out. Also, the Centres can hire out instruments, some of which are very expensive (e.g. piano, saxaphone, clarinet) - which allows parents to evaluate the commitment of their children before making a final commitment to buy. Parents are also encouraged to participate in some entry level classes with their children (e.g. recorder) to provide inspiration for practice between classes.
The current cost to parents is approximately NZ$140 per year (EUR 85) per child + instrument hire costs if applicable. The costs of the Centres and host school are subsidized by the Ministry of Education. In my opinion, it is a good model, better than teaching in large groups, providing an attractive option alongside private tuition.