My next door neighbor's son and my daughter grew up together and they both just graduated from college. How much do you recommend we give?;)

I think a meaningful gift would be better than money. Like perhaps a really nice pen set.

I would completely agree with the gift idea. There are so many things that he would need or could use into that future to remember your family by. I really like keepsakes for this purpose. Pen set is a great idea. Inscribed watches, name plates, desk mate type gift for that first big job. What a wonderful exciting time of life.

Not knowing anything about your financial situation, how close you are to the neighbor and their kid, the history (if any) of previous gift exchanges, etc - if it was me, I would suggest something between $50 and $200.

I think that's a good idea. Check out the local shopping mall, they usually have specialty stores for graduates, wedding gifts, and such. A lot of them do engraving on site.