I have done a lot of these, either with part pavers and concrete, or just all pavers. It is all in the foundation. Make sure whoever is doing it knows they need to use different sized limestone from large to small (#2's to #9's) in layers. Tamping it out every 2-3 inches for a vibrator and every 4-6 for a stomper. Then you have to make sure they lay it level and with the correct slope. No low spots, no high spots etc.
Its not that hard to do, but it will cost a decent amount of money. I could help you out and direct you to a few good companies.