The booster vaccines is cheaper even when administered at IOM and not all vaccines are repeated,further more you only get booster if your stay in Kenya exceed 3 weeks.
N/B: In mary land where my friend enrolled his children-All the three Jabs (hepatitis,Polio & TB..for children were administered for free.Other have reported it was catered for by the MEDICAID (commonly known as Obama care) which after enrolling takes effect within 2 weeks.The normal cost for vaccines in Maryland was without insurance $36.Try to Google the state you are moving to if its maryland I will give you the number of the person for more info.....