I'm not a huge sushi fan so I don't know how good tabelog is with sushi, but with many other types of food, I find it quite a decent place to start my hunt for good food.

The link below should go to an search of sushi places in tokyo with lunch course under 6000Y (should be a slider to adjust price as you see fit) sorted by tabelog score.

https://tabelog.com/en/tokyo/rstLst/...=0&SrtT=rt&PG=