Get an advocate and make the school pay for it. You will not get one without a fight. Especially with a non public agency(an outside company) you will need to do a behavior assessment probably have it done by an independent evaluator.

That's a tough one- it sounds as though he is in a public preschool if you are already in the IEP process. I'm shocked that there is a 1 to 10 ratio- any aides???
You might want to start with the behaviors and goals- if sitting and attending during circle time is on his IEP and it is not being addressed by the teacher and aides- then you have grounds to push for something more significant. Your goals will determine the services.
You might want to push for the root cause for him not sitting during circle time- sensory or behavior? What have the teachers and aides done to try to engage him? It's always EASIER to let them be- however, they are there to help him be successful in school.
You would be surprised how much sensory and OT plays into Circle Time.
I haven't heard if 1 on 1 in PreSchool (not to say that it doesn't happen). Usually the 1 on 1 is to help with attending, behavior issues (meltdowns, running off, aggressive behavior), transitioning SpEd into GenEd classrooms.
Expense- ouch! I know one aide that works for a ABA service that makes $12 an hour- not exactly skilled, I think she did attend some classes through the company. That's what the ABA company pays her- to fund a private pay ABA program it's $50K to $70K a year.
Fifteen years ago my sister hired college students (majoring in BCBA) to act for aides for my nephew and they made $12.

In ky THE school board has to pay one but u have say so about who it is.You can do it and they will pay u. Get the Law book its free and it will tell u everything I had to fight with the school but then I started recording the meeting and having my book with me and what they were suppose to do was highlighted. Then when they seen I KNEW WHAT Iwas talking about things got better.Ask the Special ED teacher how to go about it and dont take NO for an answer it will get easrier

My understanding is that you can only hire an aide/assistance if the child is in private schools. I don't think you can hire someone to work in a public school because it's a conflict of interest. You should consult a special Ed lawyer or advocate.

My son was in a private preschool before attending a special education preschool run by the San Diego Unified School District. My son has HFA and he was unable to sit in the circle time, nor stand in a line with other kids. There were only 6 children in the class room but the teacher told us that she needs an extra aid. Rather than keeping him in a private school and adding extra help with our own expense, we pulled him out of the private preschool and placed him in the special education school. He is currently in a special Ed preschool with typical peers.

With behavior strategies my son is able to sit through the circle time and is able to request for break if he needs to balance his sensory needs.