Having only one child? Good or bad?

A little history...I am the youngest of three children. My brothers and I are very close, and had a wonderful childhood. Flash forward -- I am the mother of a 2 year old little boy. His Dad is also the youngest of four and all are close. More and more I think of not having anymore children due to the economy the way it is, and the fact that my son is very active and borderline high maintenance. I just always second guess it on his behalf, I would hate to rob him of the experiences I had growing up with my brothers, and as his dad had as well. Our son has lots of cousins and we have mutual friends with kids but will he be missing out by not having a sibling?