Entry Level DSLR ... Which? (Part II)

I have written about one of the negatives of the Sony Alpha cameras in terms of lenses choice. However, my relative's Nikon D40 has this other problem, there are no ...

[-] Nikon D40: Affordable Travel Lens

My relative recently asked me how much would a 18-200mm or 18-250mm lens cost as she is interested to acquire one for her yearly traveling. She has been using her 18-55mm kit lens with her Nikon D40 and is planning to go on a safari tour. I quickly just said slightly more than USD400 as that's what the street price is for a 18-250mm lens for my Sony.
Upon looking around, realized that the 18-200mm Nikkor lens that can be used on the D40 cost slightly less than USD600! I may be wrong and may not have searched nor asked around enough but checking online and with other users, it is around that price. I haven't looked around and compare it for the Canon.