If you've been using the D40 for basic Photography or anything below professional photography or photojournalism, I'd go for the D90. On that note, if you've been using a Nikon, I'd keep using it, a) because the lenses you have now will still fit, and b) the controls and menu functions are similar. Anyway, the 90 has a better "highest quality" setting than the new 40's, 3000's, or 5000's. It also has a larger display, and the ergonomics are fixed.
a good nikon camers will cost about£600
Amazon is a good place to start to find a refurbished Nikon camera online and they offer some very good prices for a refurbished Nikon camera online as well
its a world class camera
As "good" as you want it to be.
The Nikon I105 could be a good camera for your son if he really is dedicated to learning photography. If this isn't one of his hobbies then a different camera may be better for him.
It was a good camera for its day. Check camera ratings for something more recent.
The Nikon cameras from what I have heard is a good and expensive camera. If you want to find out more reviews regarding this camera then you would have to visit the Nikon website.
The GoPro camera is a good camera and as reputable a brand as Canon and Nikon are. GoPro makes very well made and easy to use cameras that are affordable.
A good place to find a digital camera made by Nikon would be Staples. They have tons of choices and I bet they have digital cameras made by Nikon. So go take a quick look.
I find the Nikon Coolpix good for film.
Nikon digital cameras are a very good quality brand. I actually own one and love it. I print my digital photos and have to admit that I own other brands. The Nikon photo's come out with a better resolution. I have owned the camera for many years and it has outlasted many of the other digital camera's I previously owned. Nikon digital cameras are long lasting, great quality cameras.
Both they are both very good