if it's really 3.5 carat 150k sounds reasonable. A flawless, D color, excellent round cut in that size can cost up to 300k.
If you take notice, i did say IMO ( In My Opinion) I was not speaking about the ring's specifications nor was I stating that the ring does not truly cost that much. Trust me i know how expensive diamonds are, I have much experience in that field. Neil Lane (IMO) is no where near as noted as Harry Winston or GRAFF and therefore, it is not worth (IN MY OPINION) 150k.