N.W.
Just a comment about the other posts...most school "latchkey" programs are only for Kindergarten and up.
I think it is feasible to find something where you work until 3 or 3:30. You will probably have to be to work by 7 or 7:30 though.
I'm assuming he has some sort of learning disability, which is why he is bused to pre-school?
I pay 10$ an hour for a college age babysitting with a teaching degree. I would call a local university--- not sure where you live, I live close to Oakland University and ask if they have a list of nannys. My cousin found her 2 day a week nanny this way and she is awesome.
Good luck.