We were staying in the Asakusa area so this was a 10 minute walk for us. You really can't miss this street; every shop sells kitchenware, knives, tableware etc. I was hoping to buy some cute ceramic bowls, chopsticks and such but when I was there, it was a bit overwhelming going into every store. And I really didn't have too much time to browse.
We did buy 2 knives from Kamata though. I had researched beforehand and had down names of a few knife shops that were recommended. Kamata was one so we went in and after browsing and talking to the shopkeepers, bought 2 for around $100 each. My sons love using them so it was definitely a good purchase.
Other than the knives, we just bought a fake food magnet from a fake food store. The items in there are quite expensive for a souvenir, especially when you can buy something from another store that you can actually use!
We got tax refunds for the knives at an office on the street. It was an easy few minute process since no one else was in there but us.