both of my kids went to private preschool (2 days at 2, 3 days at 3 and 5 days at 4) and public kindergarten. the older one (well.. the younger one started there too) went to a private free-standing non-denominational nursery/kindergarten.. it was great, but pricey.. for 5 days we paid around 380/month, about 2.5 hours/day (this school had morning and afternoon sessions, optional lunch bunch and a "full day" kindergarten, which was on a different schedule.. later arrival than the morning kids, earlier departure than the afternoon ones). it really was a good school, and I would have liked to have kept my daughter there for kindergarten, but we couldn't afford to do that and start the younger one, and it was his turn. so.. he did a year and a half there and then we moved. he did his 4yearold year at a church preschool because there were no non-denominational ones here (neither of these facilities provided daycare), which was also pretty great (facilities-wise, the church was better, the classrooms were around the perimeter of the church gymnasium, so they had plenty of room to run and and ride and play and be loud and have "outside time", even when the weather was too lousy for them to actually go outside), and much more affordable.. 5 days was 180/month, 3 hours/day. comparable class sizes.. 18 kids, 2 teachers here, 9 kids, 1 teacher there.. which was what they had in public kindergarten too (2 different states/school systems).
mind you.. this was some years back.. I'm sure they're both more expensive now..