Shuttle bus

My ceremony site which is in the Roslyn Harbor area has really bad parking, in which we have a lot of out of town guest. We're not sure the exact amount of people we would need to accomodate w/ the bus, but we're at least looking to rent one. Can anyone give me pricing info, for a shuttle bus for at least 2hrs( maybe less), its only for pick up to go to the ceremony, then drop off, at the same location where picked up from.

Thanks