Have you looked into recycled asphalt? It seems to be getting popular around here.
Depending on where you get it, and what quality you want, it's supposed to be a longer lasting surface than rock, that can get close to or maybe even beat it in price, if the local transportation department is needing to get rid of it (or you know someone with DoT pull). There is higher quality options too, that doesn't have all the extra little debris that highway road surface has included, but of course it costs more.