Does it matter if 1 has a public dfndr as oppsd to his own attrny, n r there payment plans availbl to pay out over time for an18 yr old?

An 18 yr old called 911 on like 6 occasions, after a minor friend stole another friends cell phone, as a joke. He is also being charged for criminal mischief which he did not do, but posted the event on social media. The 18 yr old has issues as well as physical issues too. He is now facing so many counts....He is in therapy, on meds now, got a job a few days ago, and is being placed on house arrest. He has had 3 diff public defenders assigned to his case since Dec 2016. I am disabled, and cannot help him. I'm wondering if there would be any way he can get his own attorney, and pay it out over time, and how much something like this would cost, and what the particulars r, if at all possible ?