Howzit Dan,
Im in Tokyo quite often and the best shops i've seen are Pro Shop Mogi and Sansui in Shibuya. To get to Pro Shop Mogi first get to Yokohama station or Shin-Yokohama station. Shin Yokohama station would be less crowded and easier to get around. Then take the Blue Line (subway) to Azamino station which is the last stop in that direction. When you arrive in Azamino take the West Exit, as you get to the top of the stairs out of the station turn left. Once on street level you will come to a large intersection. The road forms a upside down "T" with the station to your back and a hill should be on your left, cross the street with the hill to your left and walk down the center of the "T". Stay on the left hand side of the street for 5-7 mins and you will see the sign for Pro Shop Mogi!
If you get lost go back to the station buy two beers from the vending machines find the prettiest girl you can find and ask for directions. Don't worry if she can't speak english or your native tongue its all part of the experience.
I believe there are directions to shibuya Sansui in english if you google it, very easy.
The first pic below is the sign for pro shop mogi on the side of the street, the second pic is a sample of the lures in Sansui Shibuya.
Good Luck hope you find it and don't spend the kids college tuition when you get there!