Nikon makes some good glass, but as with many companies there is a range of quality that is reflected in the price. You can't spend more than you can spend, but for the price range I'd look to the Leupold rifleman or a VX I. They and Swarovski (per consumers) are the best at honoring their warranties if there are failures. I think you might be able to buy Swarovski lens covers for that price. lol
I'm sure your son will appreciate what you get him. Many of us have used far poorer glass than your looking at for years before being able to upgrade. As stated above, quality of image and light gathering are notably better in higher end glass. The cheaper the scope, the less ability they seem to have to hold true over time--my observation anyway. I wouldn't be afraid to buy the scope your looking at.